Initial SvelteKit frontend port of windwiderstand.de

Full parity with Astro site: content rows, post/tag routes, pagination,
event badges + OSM map, comments, Live-Search via /api/search-index,
CMS image proxy, RSS, sitemap.

Deploy: Dockerfile + docker-compose.prod.yml + Gitea Actions workflow
to build + push to git.pm86.de registry and ssh-deploy to Contabo.

.gitignore

@@ -0,0 +1,21 @@
+# Dependencies
+node_modules/
+
+# Build / SvelteKit
+build/
+.svelte-kit/
+dist/
+
+# Environment
+.env
+.env.*
+!.env.example
+
+# Local / IDE
+.cache/
+.history/
+.DS_Store
+
+# Logs
+*.log
+npm-debug.log*