Add sitemap and robots

package.json

@@ -10,6 +10,7 @@
   },
   "dependencies": {
     "@astrojs/mdx": "^4.3.1",
+    "@astrojs/sitemap": "^3.4.2",
     "@iconify-json/fa": "^1.2.1",
     "@iconify-json/fa7-brands": "^1.2.0",
     "@iconify-json/fa7-solid": "^1.2.0",