refactor: 将项目迁移到 Nuxt 4

该项目从 Vue 3 迁移到了 Nuxt 4，对代码结构和配置进行了相应调整。
- 修改了环境变量前缀，将 `VITE_` 替换为 `NUXT_PUBLIC_`，以便与 Nuxt 的环境变量配置兼容。
- 添加了新的环境变量 `WAKATIME_API_KEY` 和可选变量 `WAKATIME_API_URL` 用于配置 Wakatime API。

package.json

@@ -3,27 +3,19 @@
     "private": true,
     "type": "module",
     "scripts": {
-        "dev": "vite",
-        "build": "vite build",
-        "preview": "vite preview"
+        "dev": "nuxt dev",
+        "build": "nuxt build",
+        "generate": "nuxt generate",
+        "preview": "nuxt preview"
     },
     "dependencies": {
         "@jaseeey/vue-umami-plugin": "^1.4.0",
-        "@vercel/node": "^5.5.15",
-        "cros": "^1.1.0",
-        "express": "^5.2.1",
-        "he": "^1.2.0",
         "nodemailer": "^7.0.11",
-        "vue": "^3.5.25",
-        "vue-router": "^4.6.3"
+        "nuxt": "^4.2.2"
     },
     "devDependencies": {
-        "@types/express": "^5.0.6",
         "@types/node": "^24.10.1",
         "@types/nodemailer": "^7.0.4",
-        "@vitejs/plugin-vue": "^6.0.2",
-        "typescript": "^5.9.3",
-        "vite": "^7.2.6",
-        "vue-tsc": "^3.1.6"
+        "typescript": "^5.9.3"
     }
 }