feat: implement SEO enhancements and sitemap generation

- Added comprehensive SEO meta tags in index.html for improved search engine visibility, including Open Graph and Twitter Card tags.
- Created a sitemap.xml for better indexing of site tools, generated automatically via a new script (generate-sitemap.ts).
- Introduced robots.txt to manage crawler access and specified sitemap location.
- Updated package.json to include a build step for sitemap generation and added tsx as a dependency.
- Documented SEO optimizations and usage instructions in a new SEO-README.md file.

scripts/generate-sitemap.ts

@@ -0,0 +1,83 @@
+import * as fs from 'fs';
+import * as path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+interface SitemapUrl {
+  loc: string;
+  lastmod: string;
+  changefreq: string;
+  priority: string;
+}
+
+const BASE_URL = 'https://litek.typist.cc';
+const currentDate = new Date().toISOString().split('T')[0];
+
+const tools = [
+  { path: '/tool/uuid', priority: '0.9' },
+  { path: '/tool/json', priority: '0.9' },
+  { path: '/tool/base64', priority: '0.9' },
+  { path: '/tool/network/dns', priority: '0.8' },
+  { path: '/tool/network/ping', priority: '0.8' },
+  { path: '/tool/network/tcping', priority: '0.8' },
+  { path: '/tool/network/speedtest', priority: '0.8' },
+  { path: '/tool/network/ipquery', priority: '0.8' },
+];
+
+const urls: SitemapUrl[] = [
+  {
+    loc: BASE_URL,
+    lastmod: currentDate,
+    changefreq: 'weekly',
+    priority: '1.0',
+  },
+  {
+    loc: `${BASE_URL}/tool`,
+    lastmod: currentDate,
+    changefreq: 'weekly',
+    priority: '0.9',
+  },
+];
+
+// Add all tool pages
+tools.forEach((tool) => {
+  urls.push({
+    loc: `${BASE_URL}${tool.path}`,
+    lastmod: currentDate,
+    changefreq: 'monthly',
+    priority: tool.priority,
+  });
+});
+
+function generateSitemap(): string {
+  let xml = '<?xml version="1.0" encoding="UTF-8"?>\n';
+  xml += '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">\n';
+
+  urls.forEach((url) => {
+    xml += '  <url>\n';
+    xml += `    <loc>${url.loc}</loc>\n`;
+    xml += `    <lastmod>${url.lastmod}</lastmod>\n`;
+    xml += `    <changefreq>${url.changefreq}</changefreq>\n`;
+    xml += `    <priority>${url.priority}</priority>\n`;
+    xml += '  </url>\n';
+  });
+
+  xml += '</urlset>\n';
+  return xml;
+}
+
+// Generate and write sitemap
+const sitemap = generateSitemap();
+const publicDir = path.resolve(__dirname, '../public');
+const sitemapPath = path.join(publicDir, 'sitemap.xml');
+
+// Ensure public directory exists
+if (!fs.existsSync(publicDir)) {
+  fs.mkdirSync(publicDir, { recursive: true });
+}
+
+fs.writeFileSync(sitemapPath, sitemap, 'utf-8');
+console.log(`✅ Sitemap generated successfully at ${sitemapPath}`);
+