feat(i18n): add static pre-rendering for multi-language support

- Add `generate-i18n-pages.mjs` script to pre-render localized HTML files at build time
- Add `generate-sitemap.mjs` script to generate language-aware sitemap.xml
- Create `navbar-simple.html` and `footer-simple.html` partials for simple mode
- Update all 80+ tool pages with language routing support
- Expand supported languages to 12: en, de, es, fr, it, pt, tr, vi, id, zh, zh-TW
- Update i18n.ts with new language names and support configuration
- Implement languageRouterPlugin in vite.config.ts for dev server routing
- Update nginx.conf for production static file serving from language directories
- Update TRANSLATION.md with new architecture documentation and language addition guide
- Fix relative paths in 404.html for static deployment compatibility
- Update package.json with new build scripts and dependencies
- Improves SEO through static pre-rendering and proper sitemap generation

src/pages/email-to-pdf.html

@@ -342,35 +342,35 @@
       </h2>
       <div class="grid grid-cols-2 md:grid-cols-3 lg:grid-cols-6 gap-4">
         <a
-          href="/merge-pdf.html"
+          href="merge-pdf.html"
           class="block bg-gray-800 p-4 rounded-lg hover:bg-gray-700 transition-colors border border-gray-700"
         >
           <h3 class="text-white font-semibold mb-1">Merge PDF</h3>
           <p class="text-gray-400 text-sm">Free online merge pdf tool</p>
         </a>
         <a
-          href="/word-to-pdf.html"
+          href="word-to-pdf.html"
           class="block bg-gray-800 p-4 rounded-lg hover:bg-gray-700 transition-colors border border-gray-700"
         >
           <h3 class="text-white font-semibold mb-1">Word to PDF</h3>
           <p class="text-gray-400 text-sm">Convert Word documents to PDF</p>
         </a>
         <a
-          href="/compress-pdf.html"
+          href="compress-pdf.html"
           class="block bg-gray-800 p-4 rounded-lg hover:bg-gray-700 transition-colors border border-gray-700"
         >
           <h3 class="text-white font-semibold mb-1">Compress PDF</h3>
           <p class="text-gray-400 text-sm">Free online compress pdf tool</p>
         </a>
         <a
-          href="/txt-to-pdf.html"
+          href="txt-to-pdf.html"
           class="block bg-gray-800 p-4 rounded-lg hover:bg-gray-700 transition-colors border border-gray-700"
         >
           <h3 class="text-white font-semibold mb-1">Text to PDF</h3>
           <p class="text-gray-400 text-sm">Convert text files to PDF</p>
         </a>
         <a
-          href="/edit-pdf.html"
+          href="edit-pdf.html"
           class="block bg-gray-800 p-4 rounded-lg hover:bg-gray-700 transition-colors border border-gray-700"
         >
           <h3 class="text-white font-semibold mb-1">Edit PDF</h3>