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

scripts/generate-sitemap.mjs

@@ -0,0 +1,117 @@
+import fs from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+const DIST_DIR = path.resolve(__dirname, '../dist');
+const LOCALES_DIR = path.resolve(__dirname, '../public/locales');
+const SITE_URL = process.env.SITE_URL || 'https://www.bentopdf.com';
+
+const languages = fs.readdirSync(LOCALES_DIR).filter((file) => {
+  return fs.statSync(path.join(LOCALES_DIR, file)).isDirectory();
+});
+
+const PRIORITY_MAP = {
+  index: 1.0,
+  tools: 0.9,
+  'pdf-converter': 0.9,
+  'pdf-editor': 0.9,
+  'pdf-security': 0.9,
+  'pdf-merge-split': 0.9,
+  'merge-pdf': 0.9,
+  'split-pdf': 0.9,
+  'compress-pdf': 0.9,
+  'edit-pdf': 0.9,
+  'word-to-pdf': 0.9,
+  'excel-to-pdf': 0.9,
+  'powerpoint-to-pdf': 0.9,
+  'jpg-to-pdf': 0.9,
+  'pdf-to-docx': 0.9,
+  'pdf-to-excel': 0.9,
+  'pdf-to-jpg': 0.9,
+  about: 0.8,
+  faq: 0.8,
+  contact: 0.7,
+  privacy: 0.5,
+  terms: 0.5,
+  licensing: 0.5,
+  404: 0.1,
+};
+
+function getPriority(pageName) {
+  return PRIORITY_MAP[pageName] || 0.7;
+}
+
+function buildUrl(lang, pageName) {
+  const pagePath = pageName === 'index' ? '' : pageName;
+  if (lang === 'en') {
+    return pagePath ? `${SITE_URL}/${pagePath}` : SITE_URL;
+  }
+  return pagePath ? `${SITE_URL}/${lang}/${pagePath}` : `${SITE_URL}/${lang}`;
+}
+
+function generateSitemap() {
+  console.log('🗺️  Generating multilingual sitemap...');
+  console.log(`   SITE_URL: ${SITE_URL}`);
+  console.log(`   Languages: ${languages.join(', ')}`);
+
+  // Get all HTML files from dist root (English pages)
+  const htmlFiles = fs
+    .readdirSync(DIST_DIR)
+    .filter((file) => file.endsWith('.html'))
+    .map((file) => file.replace('.html', ''));
+
+  const today = new Date().toISOString().split('T')[0];
+
+  let sitemap = `<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
+        xmlns:xhtml="http://www.w3.org/1999/xhtml">
+`;
+
+  for (const pageName of htmlFiles) {
+    const priority = getPriority(pageName);
+
+    // Generate entry for each language
+    for (const lang of languages) {
+      const url = buildUrl(lang, pageName);
+
+      sitemap += `  <url>
+    <loc>${url}</loc>
+    <lastmod>${today}</lastmod>
+    <changefreq>weekly</changefreq>
+    <priority>${priority}</priority>
+`;
+
+      // Add hreflang alternates for all languages
+      for (const altLang of languages) {
+        const altUrl = buildUrl(altLang, pageName);
+        sitemap += `    <xhtml:link rel="alternate" hreflang="${altLang}" href="${altUrl}"/>
+`;
+      }
+
+      // Add x-default pointing to English
+      const defaultUrl = buildUrl('en', pageName);
+      sitemap += `    <xhtml:link rel="alternate" hreflang="x-default" href="${defaultUrl}"/>
+  </url>
+`;
+    }
+  }
+
+  sitemap += `</urlset>
+`;
+
+  const sitemapPath = path.join(DIST_DIR, 'sitemap.xml');
+  fs.writeFileSync(sitemapPath, sitemap);
+
+  const publicSitemapPath = path.resolve(__dirname, '../public/sitemap.xml');
+  fs.writeFileSync(publicSitemapPath, sitemap);
+
+  const urlCount = htmlFiles.length * languages.length;
+  console.log(
+    `✅ Sitemap generated with ${urlCount} URLs (${htmlFiles.length} pages × ${languages.length} languages)`
+  );
+}
+
+generateSitemap();