Add PostgreSQL-backed data storage support (#444)

Co-authored-by: samanhappy <samanhappy@gmail.com>

src/dao/DatabaseDaoFactory.ts

@@ -0,0 +1,79 @@
+import { DaoFactory, UserDao, ServerDao, GroupDao, SystemConfigDao, UserConfigDao } from './index.js';
+import { UserDaoDbImpl } from './UserDaoDbImpl.js';
+import { ServerDaoDbImpl } from './ServerDaoDbImpl.js';
+import { GroupDaoDbImpl } from './GroupDaoDbImpl.js';
+import { SystemConfigDaoDbImpl } from './SystemConfigDaoDbImpl.js';
+import { UserConfigDaoDbImpl } from './UserConfigDaoDbImpl.js';
+
+/**
+ * Database-backed DAO factory implementation
+ */
+export class DatabaseDaoFactory implements DaoFactory {
+  private static instance: DatabaseDaoFactory;
+
+  private userDao: UserDao | null = null;
+  private serverDao: ServerDao | null = null;
+  private groupDao: GroupDao | null = null;
+  private systemConfigDao: SystemConfigDao | null = null;
+  private userConfigDao: UserConfigDao | null = null;
+
+  /**
+   * Get singleton instance
+   */
+  public static getInstance(): DatabaseDaoFactory {
+    if (!DatabaseDaoFactory.instance) {
+      DatabaseDaoFactory.instance = new DatabaseDaoFactory();
+    }
+    return DatabaseDaoFactory.instance;
+  }
+
+  private constructor() {
+    // Private constructor for singleton
+  }
+
+  getUserDao(): UserDao {
+    if (!this.userDao) {
+      this.userDao = new UserDaoDbImpl();
+    }
+    return this.userDao!;
+  }
+
+  getServerDao(): ServerDao {
+    if (!this.serverDao) {
+      this.serverDao = new ServerDaoDbImpl();
+    }
+    return this.serverDao!;
+  }
+
+  getGroupDao(): GroupDao {
+    if (!this.groupDao) {
+      this.groupDao = new GroupDaoDbImpl();
+    }
+    return this.groupDao!;
+  }
+
+  getSystemConfigDao(): SystemConfigDao {
+    if (!this.systemConfigDao) {
+      this.systemConfigDao = new SystemConfigDaoDbImpl();
+    }
+    return this.systemConfigDao!;
+  }
+
+  getUserConfigDao(): UserConfigDao {
+    if (!this.userConfigDao) {
+      this.userConfigDao = new UserConfigDaoDbImpl();
+    }
+    return this.userConfigDao!;
+  }
+
+  /**
+   * Reset all cached DAO instances (useful for testing)
+   */
+  public resetInstances(): void {
+    this.userDao = null;
+    this.serverDao = null;
+    this.groupDao = null;
+    this.systemConfigDao = null;
+    this.userConfigDao = null;
+  }
+}