Add CMS features with admin interface and OAuth authentication integration

- Introduced Caddy server for serving frontend and API backend.
- Implemented admin dashboard for creating, editing, and managing events.
- Replaced session-based authentication with token-based OAuth using Gitea.
- Added support for drag-and-drop event reordering in the admin interface.
- Standardized Fastify route validation with JSON schemas.
- Enhanced authentication flow with cookie-based state and secure token storage.
- Reworked backend routes to handle publishing, event management, and content updates.
- Updated `Dockerfile.caddy` and `fly.toml` for deployment configuration.

backend/package.json

@@ -16,7 +16,6 @@
     "@fastify/cors": "^9.0.1",
     "@fastify/jwt": "^8.0.0",
     "@fastify/multipart": "^8.1.0",
-    "@fastify/session": "^10.8.0",
     "bcrypt": "^5.1.1",
     "better-sqlite3": "^11.10.0",
     "drizzle-orm": "^0.33.0",