chore: overhaul infrastructure and integrate @mintel packages

- Restructure to pnpm monorepo (site moved to apps/web)
- Integrate @mintel/tsconfig, @mintel/eslint-config, @mintel/husky-config
- Implement Docker service architecture (Varnish, Directus, Gatekeeper)
- Setup environment-aware Gitea Actions deployment

apps/web/public/robots.txt

@@ -0,0 +1,4 @@
+User-agent: *
+Allow: /
+
+Sitemap: https://mintel.me/sitemap.xml