添加 backend 微服务架构：Nginx 网关 + user-service 登录注册

backend/services/user-service/migrations/001_init.sql

@@ -0,0 +1,15 @@
+-- 用户表初始化
+CREATE TABLE IF NOT EXISTS users (
+    id SERIAL PRIMARY KEY,
+    username VARCHAR(50) UNIQUE NOT NULL,
+    password_hash VARCHAR(255) NOT NULL,
+    email VARCHAR(100) UNIQUE,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
+);
+
+-- 插入测试用户（密码: 123456）
+-- bcrypt hash: $2b$12$REwMlLDCbzR4UpL6MWnzE.AacihwpFvQhGs7vDKTwwyNMb1qBWOTm
+INSERT INTO users (username, password_hash, email) 
+VALUES ('admin', '$2b$12$REwMlLDCbzR4UpL6MWnzE.AacihwpFvQhGs7vDKTwwyNMb1qBWOTm', 'admin@example.com')
+ON CONFLICT (username) DO NOTHING;