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。

nuxt.config.ts

@@ -0,0 +1,35 @@
+import { defineNuxtConfig } from "nuxt/config";
+import siteConfig from "./src/config/siteConfig";
+
+export default defineNuxtConfig({
+    compatibilityDate: "2025-12-12",
+    srcDir: "src/",
+    css: ["~/styles.css"],
+    app: {
+        head: {
+            title: siteConfig.siteMeta.title,
+            link: [{ rel: "icon", href: siteConfig.siteMeta.icon }],
+        },
+    },
+    nitro: {
+        prerender: {
+            crawlLinks: true,
+            routes: ["/sitemap.xml", "/rss.xml"],
+        },
+    },
+    runtimeConfig: {
+        smtpHost: process.env.SMTP_HOST ?? "",
+        smtpPort: Number(process.env.SMTP_PORT ?? 465),
+        smtpUser: process.env.SMTP_USER ?? "",
+        smtpPass: process.env.SMTP_PASS ?? "",
+        senderEmail: process.env.SENDER_EMAIL ?? "",
+        adminEmail: process.env.ADMIN_EMAIL ?? "",
+        smtpSecure: process.env.SMTP_SECURE ? process.env.SMTP_SECURE === "true" : undefined,
+        wakatimeApiKey: process.env.WAKATIME_API_KEY ?? "",
+        wakatimeApiUrl: process.env.WAKATIME_API_URL ?? "https://wakatime.com/api/v1",
+        public: {
+            githubToken: process.env.NUXT_PUBLIC_GITHUB_TOKEN ?? "",
+            umamiApiKey: process.env.NUXT_PUBLIC_UMAMI_API_KEY ?? "",
+        },
+    },
+});