Implement cross-domain support for OAuth and API requests

- Updated frontend to use `https://cms.gallus-pub.ch` as the API base URL.
- Configured cookies with `SameSite=None` and `Secure` for production in `auth.ts`.
- Enhanced `fly.toml` to include `FRONTEND_URL`, `CORS_ORIGIN`, and `GITEA_REDIRECT_URI`.
- Adjusted `.gitignore` to ignore `/ai/` directory.

.gitignore

@@ -22,3 +22,4 @@ pnpm-debug.log*
 
 # jetbrains setting folder
 .idea/
+/ai/