docs: 添加部署文档和 README

- 新增 DEPLOY.md 详细部署指南
- 新增 README.md 项目说明
- 更新 .env.example 添加 JWT_SECRET 示例
- 优化 db.js 数据库连接配置（支持端口和超时设置）

server/.env.example

@@ -3,3 +3,4 @@ DB_HOST=localhost
 DB_USER=root
 DB_PASSWORD=your_password_here
 DB_NAME=api_debug
+JWT_SECRET=your_jwt_secret_key_here

server/db.js

@@ -6,9 +6,13 @@ const pool = mysql.createPool({
     user: process.env.DB_USER || 'root',
     password: process.env.DB_PASSWORD || '',
     database: process.env.DB_NAME || 'api_debug',
+    port: process.env.DB_PORT || 3306,
     waitForConnections: true,
     connectionLimit: 10,
-    queueLimit: 0
+    queueLimit: 0,
+    connectTimeout: 10000,
+    acquireTimeout: 10000,
+    timeout: 10000
 });
 
 module.exports = pool;