feat: Implement ExistingDatabaseContext for managing existing databases with customizable naming strategies and auto-discovery of entities

feat: Add SqlServerSchemaProvider for extracting database schema information from SQL Server

feat: Introduce DatabaseType and NamingStrategy enums for better database management and naming conventions

feat: Create IDatabaseDiscovery and IDatabaseManager interfaces for database operations and metadata retrieval

feat: Develop REST service client architecture with BaseRestServiceClient and SAP Business One specific implementation

feat: Implement REST service discovery page with UI for connecting to SAP Business One Service Layer and displaying discovered entities

DataConnection/REST/Implementations/BaseRestServiceClient.cs

@@ -0,0 +1,119 @@
+using DataConnection.REST.Configuration;
+using DataConnection.REST.Interfaces;
+using System;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Net.Http.Json;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace DataConnection.REST.Implementations
+{
+    /// <summary>
+    /// Base implementation for a REST service client using HttpClient.
+    /// </summary>
+    public class BaseRestServiceClient : IRestServiceClient, IDisposable
+    {
+        protected readonly HttpClient _httpClient;
+        protected readonly RestServiceOptions _options;
+
+        public BaseRestServiceClient(HttpClient httpClient, RestServiceOptions options)
+        {
+            _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
+            _options = options ?? throw new ArgumentNullException(nameof(options));
+
+            ConfigureHttpClient();
+        }
+
+        protected virtual void ConfigureHttpClient()
+        {
+            if (!string.IsNullOrWhiteSpace(_options.BaseUrl))
+            {
+                _httpClient.BaseAddress = new Uri(_options.BaseUrl);
+            }
+
+            _httpClient.Timeout = TimeSpan.FromSeconds(_options.TimeoutSeconds);
+            _httpClient.DefaultRequestHeaders.Accept.Clear();
+            _httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
+
+            // Add authentication headers based on options
+            if (!string.IsNullOrWhiteSpace(_options.ApiKey))
+            {
+                // Example: Add API key header (adjust header name as needed)
+                _httpClient.DefaultRequestHeaders.TryAddWithoutValidation("X-API-KEY", _options.ApiKey);
+            }
+            else if (!string.IsNullOrWhiteSpace(_options.AuthToken))
+            {
+                _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", _options.AuthToken);
+            }
+            else if (!string.IsNullOrWhiteSpace(_options.Username) && !string.IsNullOrWhiteSpace(_options.Password))
+            {
+                var basicAuthValue = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{_options.Username}:{_options.Password}"));
+                _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", basicAuthValue);
+            }
+            // Add other authentication methods (e.g., OAuth) if necessary
+        }
+
+        public virtual async Task<T?> GetAsync<T>(string requestUri, CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                var response = await _httpClient.GetAsync(requestUri, cancellationToken);
+                response.EnsureSuccessStatusCode(); // Throws exception for non-success status codes
+                return await response.Content.ReadFromJsonAsync<T>(cancellationToken: cancellationToken);
+            }
+            catch (HttpRequestException ex)
+            {
+                // Log or handle specific HTTP request errors
+                Console.WriteLine($"HTTP Request Error: {ex.Message}");
+                // Consider custom exception handling
+                throw;
+            }
+            catch (Exception ex)
+            {
+                 // Log or handle other errors (e.g., deserialization)
+                Console.WriteLine($"Error during GET request: {ex.Message}");
+                throw;
+            }
+        }
+
+        public virtual async Task<TResponse?> PostAsync<TRequest, TResponse>(string requestUri, TRequest payload, CancellationToken cancellationToken = default)
+        {
+             try
+            {
+                var response = await _httpClient.PostAsJsonAsync(requestUri, payload, cancellationToken);
+                response.EnsureSuccessStatusCode();
+                return await response.Content.ReadFromJsonAsync<TResponse>(cancellationToken: cancellationToken);
+            }
+            catch (HttpRequestException ex)
+            {
+                Console.WriteLine($"HTTP Request Error: {ex.Message}");
+                 throw;
+            }
+            catch (Exception ex)
+            {
+                 Console.WriteLine($"Error during POST request: {ex.Message}");
+                throw;
+            }
+        }
+
+        // Implement other methods (PUT, DELETE, etc.) similarly
+
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                // HttpClient is typically managed by HttpClientFactory,
+                // but if created directly, dispose it here.
+                // _httpClient?.Dispose();
+            }
+        }
+    }
+}