A power cut makes the recordings drive's fsck slow, so the mount can
appear tens of seconds after nextnvr starts. The recorders then hit the
unmounted, root-owned mountpoint, failed mkdir, and exited permanently —
recording stayed dead until a manual restart.
- recorder: on mkdir failure, log and retry every 15s instead of exiting,
so recording resumes once storage returns
- storage: add waitForStorage() and call it before the writers start, so
startup waits (up to 120s) for the recordings dir to be present and
writable; live view still starts if storage never appears
Detect a disconnected or read-only recordings drive and surface it
without stopping recording or live view:
- storage.go: probe path existence, mount point, writability and free
space every 30s; capture mount expectation at startup so a clean
unmount (writes falling through to root fs) is also caught
- GET /api/storage endpoint; storage fields in /api/status
- red UI banner while storage is unavailable
- log ALERT on loss, OK on recovery
