chore: upgrade to nuxt 4

package.json

@@ -1,5 +1,6 @@
 {
   "private": true,
+  "type": "module",
   "scripts": {
     "build": "nuxt build",
     "dev": "nuxt dev",
@@ -8,19 +9,19 @@
   },
   "devDependencies": {
     "@nuxt/content": "^2.13.4",
-    "@nuxtjs/color-mode": "^3.5.1",
-    "@nuxtjs/sitemap": "^6.1.2",
-    "@nuxtjs/tailwindcss": "^6.12.1",
-    "@tailwindcss/typography": "^0.5.15",
+    "@nuxtjs/color-mode": "^3.5.2",
+    "@nuxtjs/sitemap": "^7.4.7",
+    "@nuxtjs/tailwindcss": "^6.14.0",
+    "@tailwindcss/typography": "^0.5.19",
     "@types/node": "^22.7.5",
-    "dayjs": "^1.11.13",
-    "nuxt": "3.13.2",
-    "prettier": "^3.3.3",
+    "dayjs": "^1.11.18",
+    "nuxt": "^4.1.3",
+    "prettier": "^3.6.2",
     "reading-time": "^2.0.0-1",
     "rehype-katex": "^7.0.1",
     "remark-math": "^6.0.0",
-    "sass": "^1.79.5",
-    "typescript": "^5.6.3",
+    "sass": "^1.93.2",
+    "typescript": "^5.9.3",
     "vite-svg-loader": "^5.1.0"
   }
 }