[Feature] Implementazione completa supporto ODBC

- Aggiunta persistenza campi ODBC (OdbcDsnName, OdbcMode) in CredentialEntity
- Creata migration EF Core per nuovi campi database
- Aggiornato mapping credenziali per caricare/salvare dati ODBC
- Creato OdbcDatabaseManager dedicato (bypass EF Core che non supporta ODBC)
- Aggiornato DataConnectionFactory per usare OdbcDatabaseManager con connessioni ODBC
- Fix auto-load DSN: sostituito @onchange con @bind-Value:after in dropdown tipo database
- Fix test connessione SAP HANA: rimossa query SELECT 1 che causava errori sintassi
- Implementati tutti i metodi IDatabaseManager in OdbcDatabaseManager
- Supporto completo per discovery schema, tabelle e query ODBC

Risolve problema DbContext non configurato per ODBC e abilita connessioni ODBC complete.

CredentialManager/Services/CredentialService.cs

@@ -89,6 +89,8 @@ public class CredentialService : ICredentialService
                 AdditionalParameters = credential.AdditionalParameters != null 
                     ? JsonSerializer.Serialize(credential.AdditionalParameters) 
                     : null,
+                OdbcDsnName = credential.OdbcDsnName,
+                OdbcMode = credential.OdbcMode.ToString(),
                 CreatedAt = DateTime.UtcNow,
                 CreatedBy = Environment.UserName
             };
@@ -110,6 +112,8 @@ public class CredentialService : ICredentialService
                 existing.CommandTimeout = entity.CommandTimeout;
                 existing.IgnoreSslErrors = entity.IgnoreSslErrors;
                 existing.AdditionalParameters = entity.AdditionalParameters;
+                existing.OdbcDsnName = entity.OdbcDsnName;
+                existing.OdbcMode = entity.OdbcMode;
                 existing.UpdatedAt = DateTime.UtcNow;
                 
                 _context.Credentials.Update(existing);
@@ -695,7 +699,11 @@ public class CredentialService : ICredentialService
             Password = DecryptSafely(entity.EncryptedPassword, entity.Name, "password"),
             ConnectionString = entity.ConnectionString,
             CommandTimeout = entity.CommandTimeout,
-            IgnoreSslErrors = entity.IgnoreSslErrors
+            IgnoreSslErrors = entity.IgnoreSslErrors,
+            OdbcDsnName = entity.OdbcDsnName,
+            OdbcMode = !string.IsNullOrEmpty(entity.OdbcMode) && Enum.TryParse<OdbcConnectionMode>(entity.OdbcMode, out var odbcMode)
+                ? odbcMode
+                : OdbcConnectionMode.Dsn
         };
 
         if (!string.IsNullOrEmpty(entity.AdditionalParameters))