pi-ele Phase 1: Electron 骨架（主进程+托盘+preload，可复用 web/src）

- web/electron/main.cjs: BrowserWindow 加载 dist/index.html（prod）或 vite dev server
  托盘（进托盘/退出/单击恢复），关闭按钮隐藏到托盘而非退出（用户要求）
- web/electron/preload.cjs: contextBridge 暴露 gatewayUrl/versions/platform
- web/package.json: 加 main 指向 main.cjs、dev:electron / build:win / build:linux 脚本、
  electron 44.2.0 + electron-builder 26.15.3 依赖、build 配置（NSIS/AppImage/deb）
- .gitignore: /release/

验证（headless + xvfb）：
- Electron 加载 Gateway WebUI 成功（title=AgentMail, body 渲染）
- Tray API 可用，BrowserWindow 正常
- prod 模式真实 main.cjs 无报错

web/package.json

@@ -3,9 +3,13 @@
   "version": "0.1.0",
   "private": true,
   "type": "module",
+  "main": "electron/main.cjs",
   "scripts": {
     "dev": "vite",
+    "dev:electron": "ELECTRON_START_URL=http://localhost:5173 electron electron/main.cjs",
     "build": "vite build",
+    "build:win": "vite build && electron-builder --win",
+    "build:linux": "vite build && electron-builder --linux",
     "preview": "vite preview",
     "typecheck": "tsc --noEmit",
     "test": "node test/markdown-xss.test.mjs && node test/narrow-layout.test.mjs && node test/theme.test.mjs && vitest run",
@@ -31,11 +35,41 @@
     "@types/react-dom": "^18.3.0",
     "@vitejs/plugin-react": "^4.3.1",
     "autoprefixer": "^10.4.19",
+    "electron": "^44.2.0",
+    "electron-builder": "^26.15.3",
     "jsdom": "26.1.0",
     "postcss": "^8.4.39",
     "tailwindcss": "^3.4.6",
     "typescript": "^5.5.3",
     "vite": "^5.3.4",
     "vitest": "3.2.4"
+  },
+  "build": {
+    "appId": "xyz.jianfgit.agentmail",
+    "productName": "AgentMail",
+    "files": [
+      "dist/**/*",
+      "electron/**/*"
+    ],
+    "directories": {
+      "buildResources": "src/icons",
+      "output": "release"
+    },
+    "win": {
+      "target": [
+        { "target": "nsis", "arch": ["x64"] }
+      ]
+    },
+    "linux": {
+      "target": [
+        { "target": "AppImage", "arch": ["x64"] },
+        { "target": "deb", "arch": ["x64"] }
+      ],
+      "category": "Network"
+    },
+    "nsis": {
+      "oneClick": false,
+      "allowToChangeInstallationDirectory": true
+    }
   }
-}
+}