Fix installation and startup

Run these commands from apps/subtitles/ using the same Compose project and files as the installation:

docker compose ps
docker compose logs --tail 100 kinosail
docker compose exec -T kinosail kinosail healthcheck

Check that the engine/VM is running, port 38128 is available, the host media directory exists, and container file sharing allows access. The default source setup binds its web port to localhost.

If startup names /run/secrets/kinosail_backup_key as missing, the release secret-file setting was copied without a corresponding mount. Clear that setting for the source quickstart, or mount and configure the actual key as described in backups.

If setup reappears unexpectedly after an update, check the Compose project and /config volume before creating another Owner. Do not remove volumes while diagnosing.