Enable KeyStatic CMS for production

Changes:
- Added Netlify adapter for server-side rendering
- Changed output mode from static to server
- Updated KeyStatic storage from local to GitHub
- Removed SKIP_KEYSTATIC from Netlify build
- KeyStatic Admin UI will be available at /keystatic

Features:
- Server-side rendering with Netlify Functions
- GitHub integration for content management
- Production-ready KeyStatic Admin UI

Co-Authored-By: Claude <noreply@anthropic.com>

.netlify/v1/config.json

@@ -0,0 +1 @@
+{"images":{"remote_images":["https?://cdn\\.pixabay\\.com/.*"]},"headers":[{"for":"/_astro/*","values":{"Cache-Control":"public, max-age=31536000, immutable"}}]}