🧬 refactor: Wire Database Methods into MCP Package via Registry Pattern (#10715)

* Refactor: MCPServersRegistry Singleton Pattern with Dependency Injection for DB methods consumption

* refactor: error handling in MCP initialization and improve logging for MCPServersRegistry instance creation.

- Added checks for mongoose instance in ServerConfigsDB constructor and refined error messages for clarity.
- Reorder and use type imports

---------

Co-authored-by: Atef Bellaaj <slalom.bellaaj@external.daimlertruck.com>
Co-authored-by: Danny Avila <danny@librechat.ai>

packages/api/src/mcp/__tests__/ConnectionsRepository.test.ts

@@ -21,18 +21,21 @@ jest.mock('../MCPConnectionFactory', () => ({
 jest.mock('../connection');
 
 // Mock the registry
+const mockRegistryInstance = {
+  getServerConfig: jest.fn(),
+  getAllServerConfigs: jest.fn(),
+};
+
 jest.mock('../registry/MCPServersRegistry', () => ({
-  mcpServersRegistry: {
-    getServerConfig: jest.fn(),
-    getAllServerConfigs: jest.fn(),
+  MCPServersRegistry: {
+    getInstance: () => mockRegistryInstance,
   },
 }));
 
 const mockLogger = logger as jest.Mocked<typeof logger>;
 
-// Import mocked registry
-import { mcpServersRegistry as registry } from '../registry/MCPServersRegistry';
-const mockRegistry = registry as jest.Mocked<typeof registry>;
+// Use mocked registry instance
+const mockRegistry = mockRegistryInstance as jest.Mocked<typeof mockRegistryInstance>;
 
 describe('ConnectionsRepository', () => {
   let repository: ConnectionsRepository;