feat(updater): 前端 Updater 封装与设置页接入\n\n- 新增 src/lib/updater.ts（check→download→install→relaunch 封装与类型）\n- SettingsModal 按钮优先走 Updater，失败回退打开 Releases\n- 依赖：@tauri-apps/plugin-updater、@tauri-apps/plugin-process\n- 文档：精简并重写 docs/updater-plan.md（明确接口/流程/配置）

package.json

@@ -32,6 +32,8 @@
     "@codemirror/view": "^6.38.2",
     "@tailwindcss/vite": "^4.1.13",
     "@tauri-apps/api": "^2.8.0",
+    "@tauri-apps/plugin-process": "^2.0.0",
+    "@tauri-apps/plugin-updater": "^2.0.0",
     "codemirror": "^6.0.2",
     "lucide-react": "^0.542.0",
     "react": "^18.2.0",