Peter Meier
56084ac542
Adds a self-contained maintenance page that the SvelteKit handle hook serves before the first CMS call when `isCmsAvailable()` returns false. The probe hits `/api-docs/openapi.json` with a short timeout and caches the result (10s healthy, 3s unhealthy) so we don't pay a round-trip per request. `/maintenance` and `?cms_down=1` simulate the page without taking the CMS down — useful for previewing the copy. The maintenance HTML is fully inline (no CMS calls, no layout, no external CSS) so it survives even when every dependency is down. Returned with 503 + Retry-After:60 + noindex headers. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>