feat: 开机自启功能（tauri-plugin-autostart）

- Cargo.toml: 添加 tauri-plugin-autostart 依赖（桌面端）
- lib.rs: 初始化 autostart 插件（MacosLauncher::LaunchAgent）
- capabilities/default.json: 添加 autostart 权限
- settings.js: 面板设置新增开机自启开关（仅 Tauri 模式显示）
- package.json: 添加 @tauri-apps/plugin-autostart 前端依赖

package-lock.json

@@ -1,15 +1,16 @@
 {
   "name": "clawpanel",
-  "version": "0.7.2",
+  "version": "0.9.9",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "clawpanel",
-      "version": "0.7.2",
+      "version": "0.9.9",
       "license": "AGPL-3.0",
       "dependencies": {
         "@tauri-apps/api": "^2.5.0",
+        "@tauri-apps/plugin-autostart": "^2.5.1",
         "@tauri-apps/plugin-shell": "^2.2.1"
       },
       "devDependencies": {
@@ -1036,6 +1037,15 @@
         "node": ">= 10"
       }
     },
+    "node_modules/@tauri-apps/plugin-autostart": {
+      "version": "2.5.1",
+      "resolved": "https://registry.npmjs.org/@tauri-apps/plugin-autostart/-/plugin-autostart-2.5.1.tgz",
+      "integrity": "sha512-zS/xx7yzveCcotkA+8TqkI2lysmG2wvQXv2HGAVExITmnFfHAdj1arGsbbfs3o6EktRHf6l34pJxc3YGG2mg7w==",
+      "license": "MIT OR Apache-2.0",
+      "dependencies": {
+        "@tauri-apps/api": "^2.8.0"
+      }
+    },
     "node_modules/@tauri-apps/plugin-shell": {
       "version": "2.3.5",
       "resolved": "https://registry.npmjs.org/@tauri-apps/plugin-shell/-/plugin-shell-2.3.5.tgz",