Add a scan->notify->web end-to-end smoke test against a seeded :memory: DB,
fix .gitignore so the cmd/naviwatcher source dir is not excluded by the
root binary rule, and document the new sync.interval field in config.yaml.example.
- Store cached_at in canonical UTC layout so the cache TTL cutoff comparison is a valid time ordering (previously go-sqlite3 serialized time.Time as RFC3339, making the space-separated cutoff match only by ASCII accident; same-day expired entries were falsely served as fresh).
- Remove stale no-op scanner config keys (ignore_bootlegs, include_compilations) from config.yaml.example and docs; these fields were removed from ScannerConfig but left in configs, silently doing nothing.