Resolves the SonarQube go:S3776 cognitive-complexity finding on
RecordInventory by replacing the pvc.Healthy if/else with a boolGauge
helper. Adds tests locking the pvc_backup_health gauge to exactly 1 for
healthy and 0 for unhealthy with unchanged metric identity and labels.
Closes#9
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>