Add authentication, user management, and database migration features

- Implement OAuth 2.0 and PAT authentication methods
- Add user management, roles, and profile functionality
- Add database migrations and admin user scripts
- Update services for authentication and user settings
- Add protected routes and permission hooks
- Update documentation for authentication and database access

backend/src/services/database/factory.ts

@@ -16,8 +16,9 @@ const __dirname = dirname(__filename);
 
 /**
  * Create a database adapter based on environment variables
+ * @param allowClose - If false, the adapter won't be closed when close() is called (for singletons)
  */
-export function createDatabaseAdapter(dbType?: string, dbPath?: string): DatabaseAdapter {
+export function createDatabaseAdapter(dbType?: string, dbPath?: string, allowClose: boolean = true): DatabaseAdapter {
   const type = dbType || process.env.DATABASE_TYPE || 'sqlite';
   const databaseUrl = process.env.DATABASE_URL;
 
@@ -33,11 +34,11 @@ export function createDatabaseAdapter(dbType?: string, dbPath?: string): Databas
 
       const constructedUrl = `postgresql://${user}:${password}@${host}:${port}/${name}${ssl}`;
       logger.info('Creating PostgreSQL adapter with constructed connection string');
-      return new PostgresAdapter(constructedUrl);
+      return new PostgresAdapter(constructedUrl, allowClose);
     }
 
     logger.info('Creating PostgreSQL adapter');
-    return new PostgresAdapter(databaseUrl);
+    return new PostgresAdapter(databaseUrl, allowClose);
   }
 
   // Default to SQLite