fix: set canonical domain to braboj.me

Updates site URL so sitemap, canonical tags, and OG URLs
point to the custom domain instead of braboj.github.io.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: braboj

astro-site/astro.config.mjs

@@ -5,7 +5,7 @@ import { remarkRewriteLinks } from './src/plugins/remark-rewrite-links.ts';
 
 // https://astro.build/config
 export default defineConfig({
-  site: 'https://braboj.github.io',
+  site: 'https://braboj.me',
   base: '/tutorial-git/',
   trailingSlash: 'always',
   integrations: [sitemap()],