chore: update Dockerfile for pnpm, modify package.json dependencies, and implement rate limiting

- Switched from npm to pnpm for dependency management in Dockerfile, improving build efficiency.
- Updated Vue and Vue Router versions in package.json for better compatibility.
- Changed placeholder URLs in site.ts to actual Fiverr links and adjusted review count.
- Removed obsolete sitemap.xml file to streamline the project.
- Added a new rate limiting plugin to manage API request limits for the contact endpoint.

package.json

@@ -21,8 +21,8 @@
     "nodemailer": "^8.0.5",
     "nuxt": "^4.0.0",
     "nuxt-gtag": "^4.1.0",
-    "vue": "latest",
-    "vue-router": "latest",
+    "vue": "^3.5.0",
+    "vue-router": "^4.5.0",
     "zod": "^4.3.6"
   },
   "devDependencies": {