Add auto sitemap generation (#168)

This commit adds a sitemap.xml to improve SEO for our project. By
using Next.js, we leverage the next-sitemap package
(https://www.npmjs.com/package/next-sitemap) to automatically generate
the sitemap during the build process.

Additionally, a robots.txt file has also been automatically created to
guide search engine crawlers.

.gitignore

@@ -79,3 +79,7 @@ tags
 .ionide
 
 # End of https://www.toptal.com/developers/gitignore/api/vim,visualstudiocode
+
+# Autogenerated files
+sitemap.xml
+robots.txt

next-sitemap.config.js

@@ -0,0 +1,6 @@
+/** @type {import('next-sitemap').IConfig} */
+module.exports = {
+  siteUrl: process.env.NEXT_PUBLIC_SITE_URL,
+  generateRobotsTxt: true,
+  generateIndexSitemap: false,
+};

package.json

@@ -4,8 +4,8 @@
   "private": true,
   "scripts": {
     "dev": "next dev",
-    "build": "next build",
-    "export": "next build && next export",
+    "build": "next build && next-sitemap",
+    "export": "next build && next-sitemap && next export",
     "start": "next start",
     "lint": "next lint",
     "fetch:ui": "./scripts/fetch-ui.sh",
@@ -25,6 +25,7 @@
     "next-image-export-optimizer": "^1.0.1",
     "next-mdx-remote": "^4.1.0",
     "next-remote-watch": "^2.0.0",
+    "next-sitemap": "^4.2.3",
     "prism-react-renderer": "^1.3.5",
     "prismjs": "^1.29.0",
     "react": "18.2.0",