Update package dependencies and enhance development setup

- Added `browser-sync` and `concurrently` as devDependencies for improved development workflow.
- Updated the `dev` script to run the build process and start a live server concurrently.
- Enhanced the about page with a link to the source code repository hosted on a self-managed Gitea instance.

package.json

@@ -5,11 +5,15 @@
   "type": "module",
   "scripts": {
     "build": "node build.js",
-    "dev": "node build.js --watch",
+    "dev": "concurrently \"node build.js --watch\" \"browser-sync start --server dist --files dist --no-open\"",
     "serve": "npx --yes serve dist -p 3000"
   },
   "dependencies": {
     "gray-matter": "^4.0.3",
     "marked": "^12.0.0"
+  },
+  "devDependencies": {
+    "browser-sync": "^3.0.2",
+    "concurrently": "^8.2.2"
   }
 }