新增: MySQL/SSH 代理工具

- mysql-proxy: MySQL HTTP 代理，连接池复用
- ssh-proxy: SSH HTTP 代理，会话复用
- mysql-cli: 轻量级 MySQL CLI 工具

功能特性:
- 延迟初始化，启动快
- CLI 和 HTTP API 双模式
- 请求日志支持
- 错误友好提示
- JSON 极简输出格式

mysql-proxy/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "mysql-proxy"
+version = "0.1.0"
+edition = "2021"
+description = "MySQL HTTP proxy with connection pooling"
+
+[dependencies]
+mysql = "25"
+tokio = { version = "1", features = ["full"] }
+axum = "0.7"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+toml = "0.8"
+anyhow = "1"
+clap = { version = "4", features = ["derive"] }
+ureq = "2"  # CLI HTTP client (2.x has simpler API)
+
+[profile.release]
+opt-level = "z"
+lto = true
+strip = true