[Feature/Perf] Ottimizzazioni bulk pre-discovery, batch deletion sync e supporto OLE DB / Salesforce client_credentials

## Bulk Pre-Discovery e riduzione query SQLite/SOQL

### KeyAssociationService — FindAssociationsByKeyValuesBulkAsync (nuovo)
- Aggiunta query bulk 'WHERE KeyValue IN (...)' per recuperare N associazioni con 1 sola query SQLite
  (chunking a 500 chiavi per rispettare il limite ~999 parametri di SQLite)
- Aggiunta interfaccia IKeyAssociationService e delegata in DataConnectionCredentialService / IDataConnectionCredentialService

### AssociationService — BatchFindOrCreateAssociationsAsync (nuovo)
- Nuovo metodo bulk che sostituisce i loop per-record durante l'analisi composite:
  1) 1 query SQLite bulk per tutte le chiavi
  2) Per le chiavi non trovate: SOQL 'IN (...)' su Salesforce in chunk da 200 via BatchExecuteQueriesAsync
     (ceil(K/25) HTTP Composite call invece di K singole)
  3) Salvataggio parallelo delle associazioni pre-discovery scoperte
- Fallback per-record automatico per client REST non Salesforce
- Aggiornata interfaccia IAssociationService con documentazione XML completa

### DataCoupler.razor.cs — STEP A/B nel flusso COMPOSITE
- Pre-Discovery spostata FUORI dal loop parallelo (STEP A, prima dell'analisi)
- associationsByKey pre-popolato con BatchFindOrCreateAssociationsAsync
- STEP B: il loop parallelo usa TryGetValue O(1) invece di query async per record
- Rimozione blocco ~40 righe di per-record lookup / fallback duplicati

## Salesforce Composite API — Batch Delete e Patch

### SalesforceServiceClient — metodi batch (nuovi)
- BatchDeleteEntitiesAsync: elimina N record con ceil(N/25) Composite call invece di N
- BatchPatchSingleFieldAsync: aggiorna un singolo campo su N record tramite BatchUpdateEntitiesAsync

### DeletionSyncService — refactoring batch
- ExecuteBatchedSalesforceDeletionsAsync: orchestrazione batch per Delete / Deactivate / Mark su Salesforce
- ExecuteSequentialDeletionsAsync: loop sequenziale esistente estratto in metodo riutilizzabile
- Dispatcher: Salesforce -> batch Composite, altri client REST -> sequenziale

## Supporto OLE DB (database)

### DatabaseSchemaProviderFactory
- Aggiunto case DatabaseType.OleDb -> new OleDbSchemaProvider() nel factory switch

### DatabaseMethod.cs
- Aggiunto metodo IsOleDbConnection() (parallelo a IsOdbcConnection())
- Query validation e manager temporaneo estesi a OLE DB oltre che ODBC
- GetLimitedQuery: aggiunto case OleDb -> 'SELECT TOP N FROM (subquery)'

## Salesforce OAuth2 — fix client_credentials

### CredentialService.cs
- Aggiunto 'GrantType' alla HashSet serviceSpecificKeys per preservarlo nella serializzazione AdditionalParameters

### DataConnectionCredentialService.cs
- Refactored BuildRestServiceOptions in helper statico riutilizzato da entrambi i metodi GetRestServiceOptions
- Mapping coerente ClientId/ClientSecret/GrantType per Salesforce (allineato a DataConnectionFactory)
- TestSalesforceOAuthLogin: branch esplicito per client_credentials (no username/password/token)
  con validazione preventiva ClientId+ClientSecret obbligatori
- Log flow label (password|client_credentials) in tutti i messaggi di autenticazione

## VS Code tasks

### .vscode/tasks.json
- Rimosso task generico 'Publish Data_Coupler'
- Aggiunti due task separati: win-x64 e win-x86, entrambi SingleFile + Self-Contained + ReadyToRun

DataConnection/CredentialManagement/Interfaces/IDataConnectionCredentialService.cs

@@ -85,6 +85,14 @@ public interface IDataConnectionCredentialService
     Task<KeyAssociation?> FindKeyAssociationByValueParallelAsync(string keyValue);
     Task<bool> DeleteKeyAssociationParallelAsync(int id);
 
+    /// <summary>
+    /// Bulk lookup associazioni - una sola query SQLite per N chiavi.
+    /// </summary>
+    Task<Dictionary<string, KeyAssociation>> FindKeyAssociationsByValuesBulkAsync(
+        IEnumerable<string> keyValues,
+        string destinationEntity,
+        string restCredentialName);
+
     // Deletion synchronization operations
     Task<int> MarkDeletedAssociationsAsync(List<string> sourceKeyValues, string destinationEntity, string restCredentialName);
     Task<List<KeyAssociation>> GetPendingDeletionsAsync(string destinationEntity, string restCredentialName);

DataConnection/CredentialManagement/Services/DataConnectionCredentialService.cs

@@ -168,16 +168,7 @@ public class DataConnectionCredentialService : IDataConnectionCredentialService
         if (credential == null)
             throw new InvalidOperationException($"REST API credential '{credentialName}' not found");
 
-        var options = new DataConnection.REST.Configuration.RestServiceOptions
-        {
-            BaseUrl = credential.BaseUrl,
-            ApiKey = credential.ApiKey,
-            Username = credential.Username,
-            Password = credential.Password,
-            AuthToken = credential.AuthToken,
-            TimeoutSeconds = credential.TimeoutSeconds,
-            IgnoreSslErrors = credential.IgnoreSslErrors
-        };
+        var options = BuildRestServiceOptions(credential);
 
         _logger.LogDebug("Created RestServiceOptions for credential: {Name} ({BaseUrl})",
             credentialName, credential.BaseUrl);
@@ -191,19 +182,42 @@ public class DataConnectionCredentialService : IDataConnectionCredentialService
         if (credential == null)
             throw new InvalidOperationException($"REST API credential with ID '{credentialId}' not found");
 
+        var options = BuildRestServiceOptions(credential);
+
+        _logger.LogDebug("Created RestServiceOptions for credential ID: {Id} ({BaseUrl})",
+            credentialId, credential.BaseUrl);
+        return options;
+    }
+
+    private static DataConnection.REST.Configuration.RestServiceOptions BuildRestServiceOptions(RestApiCredential credential)
+    {
         var options = new DataConnection.REST.Configuration.RestServiceOptions
         {
             BaseUrl = credential.BaseUrl,
-            ApiKey = credential.ApiKey,
             Username = credential.Username,
             Password = credential.Password,
-            AuthToken = credential.AuthToken,
             TimeoutSeconds = credential.TimeoutSeconds,
             IgnoreSslErrors = credential.IgnoreSslErrors
         };
 
-        _logger.LogDebug("Created RestServiceOptions for credential ID: {Id} ({BaseUrl})",
-            credentialId, credential.BaseUrl);
+        // Mapping coerente con DataConnectionFactory.CreateRestServiceClientAsync
+        switch (credential.ServiceType)
+        {
+            case RestServiceType.Salesforce:
+                options.ApiKey = credential.ClientId;
+                options.AuthToken = credential.ClientSecret;
+                options.SalesforceGrantType = credential.GrantType;
+                break;
+            case RestServiceType.SapB1ServiceLayer:
+                options.ApiKey = credential.CompanyDatabase;
+                options.AuthToken = credential.AuthToken;
+                break;
+            default:
+                options.ApiKey = credential.ApiKey;
+                options.AuthToken = credential.AuthToken;
+                break;
+        }
+
         return options;
     }
 
@@ -550,8 +564,8 @@ public class DataConnectionCredentialService : IDataConnectionCredentialService
     {
         try
         {
-            _logger.LogInformation("Testing Salesforce authentication for {Name} ({BaseUrl})",
-                credential.Name, credential.BaseUrl);
+            _logger.LogInformation("Testing Salesforce authentication for {Name} ({BaseUrl}, GrantType={GrantType})",
+                credential.Name, credential.BaseUrl, credential.GrantType);
 
             _logger.LogDebug("Salesforce credential details: Username={Username}, HasPassword={HasPassword}, HasSecurityToken={HasSecurityToken}, HasClientId={HasClientId}, HasClientSecret={HasClientSecret}",
                 credential.Username, !string.IsNullOrEmpty(credential.Password), !string.IsNullOrEmpty(credential.SecurityToken),
@@ -560,49 +574,69 @@ public class DataConnectionCredentialService : IDataConnectionCredentialService
             using var httpClient = new HttpClient();
             httpClient.Timeout = TimeSpan.FromSeconds(credential.TimeoutSeconds);
 
-            // Test di autenticazione OAuth2
             var tokenUrl = credential.BaseUrl.TrimEnd('/') + "/services/oauth2/token";
-            var tokenData = new List<KeyValuePair<string, string>>
-            {
-                new("grant_type", "password"),
-                new("username", credential.Username ?? "")
-            };
+            List<KeyValuePair<string, string>> tokenData;
+            string flowLabel;
 
-            // Aggiungiamo password + security token se disponibile
-            var password = credential.Password ?? "";
-            if (!string.IsNullOrEmpty(credential.SecurityToken))
+            if (credential.GrantType == CredentialManager.Models.SalesforceGrantType.ClientCredentials)
             {
-                password += credential.SecurityToken;
-            }
-            tokenData.Add(new("password", password));
+                // Client Credentials flow — server-to-server, no user
+                if (string.IsNullOrEmpty(credential.ClientId) || string.IsNullOrEmpty(credential.ClientSecret))
+                {
+                    return (false, "Flusso client_credentials richiede ClientId e ClientSecret configurati.");
+                }
 
-            // Aggiungiamo client credentials se disponibili
-            if (!string.IsNullOrEmpty(credential.ClientId))
-            {
-                tokenData.Add(new("client_id", credential.ClientId));
+                tokenData = new List<KeyValuePair<string, string>>
+                {
+                    new("grant_type", "client_credentials"),
+                    new("client_id", credential.ClientId),
+                    new("client_secret", credential.ClientSecret)
+                };
+                flowLabel = "client_credentials";
             }
-            if (!string.IsNullOrEmpty(credential.ClientSecret))
+            else
             {
-                tokenData.Add(new("client_secret", credential.ClientSecret));
+                // Password flow (default)
+                var password = credential.Password ?? "";
+                if (!string.IsNullOrEmpty(credential.SecurityToken))
+                {
+                    password += credential.SecurityToken;
+                }
+
+                tokenData = new List<KeyValuePair<string, string>>
+                {
+                    new("grant_type", "password"),
+                    new("username", credential.Username ?? ""),
+                    new("password", password)
+                };
+
+                if (!string.IsNullOrEmpty(credential.ClientId))
+                {
+                    tokenData.Add(new("client_id", credential.ClientId));
+                }
+                if (!string.IsNullOrEmpty(credential.ClientSecret))
+                {
+                    tokenData.Add(new("client_secret", credential.ClientSecret));
+                }
+                flowLabel = "password";
             }
 
-            _logger.LogDebug("Posting to Salesforce token URL: {TokenUrl}", tokenUrl);
+            _logger.LogDebug("Posting to Salesforce token URL: {TokenUrl} (flow={Flow})", tokenUrl, flowLabel);
 
             var tokenContent = new FormUrlEncodedContent(tokenData);
             var response = await httpClient.PostAsync(tokenUrl, tokenContent);
 
             if (response.IsSuccessStatusCode)
             {
-                var responseContent = await response.Content.ReadAsStringAsync();
-                _logger.LogInformation("Salesforce authentication successful for {Name}", credential.Name);
-                return (true, $"Autenticazione Salesforce riuscita!\n\nDettagli:\n- Login URL: {credential.BaseUrl}\n- API Version: {credential.ApiVersion}\n- Sandbox: {credential.IsSandbox}\n- Tipo Auth: OAuth2\n- Timeout: {credential.TimeoutSeconds}s");
+                _logger.LogInformation("Salesforce authentication ({Flow}) successful for {Name}", flowLabel, credential.Name);
+                return (true, $"Autenticazione Salesforce riuscita!\n\nDettagli:\n- Login URL: {credential.BaseUrl}\n- API Version: {credential.ApiVersion}\n- Sandbox: {credential.IsSandbox}\n- Tipo Auth: OAuth2 ({flowLabel})\n- Timeout: {credential.TimeoutSeconds}s");
             }
             else
             {
                 var errorContent = await response.Content.ReadAsStringAsync();
-                _logger.LogWarning("Salesforce authentication failed for {Name}. Status: {StatusCode}, Response: {Response}",
-                    credential.Name, response.StatusCode, errorContent);
-                return (false, $"Autenticazione Salesforce fallita. Status: {response.StatusCode}\nDettagli: {errorContent}");
+                _logger.LogWarning("Salesforce authentication ({Flow}) failed for {Name}. Status: {StatusCode}, Response: {Response}",
+                    flowLabel, credential.Name, response.StatusCode, errorContent);
+                return (false, $"Autenticazione Salesforce ({flowLabel}) fallita. Status: {response.StatusCode}\nDettagli: {errorContent}");
             }
         }
         catch (HttpRequestException ex)
@@ -1074,6 +1108,14 @@ public class DataConnectionCredentialService : IDataConnectionCredentialService
         return await _keyAssociationService.FindAssociationByKeyValueParallelAsync(keyValue);
     }
 
+    public async Task<Dictionary<string, KeyAssociation>> FindKeyAssociationsByValuesBulkAsync(
+        IEnumerable<string> keyValues,
+        string destinationEntity,
+        string restCredentialName)
+    {
+        return await _keyAssociationService.FindAssociationsByKeyValuesBulkAsync(keyValues, destinationEntity, restCredentialName);
+    }
+
     public async Task<bool> DeleteKeyAssociationParallelAsync(int id)
     {
         return await _keyAssociationService.DeleteAssociationParallelAsync(id);