feat(proxy): cleanup proxy server on app exit and remove unused non-takeover mode

- Add cleanup_before_exit() to gracefully stop proxy and restore live configs
- Handle ExitRequested event to catch Cmd+Q, Alt+F4, and tray quit
- Use std::process::exit(0) after cleanup to avoid infinite loop
- Remove unused start_proxy_server and stop_proxy_server commands
- Remove unused startMutation and stopMutation from useProxyStatus hook
- Simplify API to only expose takeover mode (start_proxy_with_takeover/stop_proxy_with_restore)

src-tauri/src/commands/proxy.rs

@@ -7,14 +7,6 @@ use crate::proxy::types::*;
 use crate::proxy::{CircuitBreakerConfig, CircuitBreakerStats};
 use crate::store::AppState;
 
-/// 启动代理服务器
-#[tauri::command]
-pub async fn start_proxy_server(
-    state: tauri::State<'_, AppState>,
-) -> Result<ProxyServerInfo, String> {
-    state.proxy_service.start().await
-}
-
 /// 启动代理服务器（带 Live 配置接管）
 #[tauri::command]
 pub async fn start_proxy_with_takeover(
@@ -23,12 +15,6 @@ pub async fn start_proxy_with_takeover(
     state.proxy_service.start_with_takeover().await
 }
 
-/// 停止代理服务器
-#[tauri::command]
-pub async fn stop_proxy_server(state: tauri::State<'_, AppState>) -> Result<(), String> {
-    state.proxy_service.stop().await
-}
-
 /// 停止代理服务器（恢复 Live 配置）
 #[tauri::command]
 pub async fn stop_proxy_with_restore(state: tauri::State<'_, AppState>) -> Result<(), String> {