Configure remote database connection and update documentation

backend/dist/modules/users/users.service.d.ts

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+import { Repository } from 'typeorm';
+import { User } from './entities/user.entity';
+export declare class UsersService {
+    private usersRepository;
+    constructor(usersRepository: Repository<User>);
+    create(username: string, email: string, password: string): Promise<User>;
+    findAll(): Promise<User[]>;
+    findOne(id: string): Promise<User>;
+    findByUsername(username: string): Promise<User | null>;
+    findByEmail(email: string): Promise<User | null>;
+    update(id: string, updateData: Partial<User>): Promise<User>;
+    updateOnlineStatus(id: string, isOnline: boolean): Promise<void>;
+}