- Enforce positive bundle size, matching SHA-256, user-scoped object keys, and legacyUnverified status for historical bundles in R2UploadService and FirebaseSyncProvider
- Update SyncManager reconciliation to accept legacyUnverified status, mark historical rides as synced without re-upload, and track legacy unverified counts
- Add 18-test vitest suite for Cloudflare Worker /r2/verify endpoint covering CORS, auth, validation, ownership, HEAD/GET, legacy bundles, and errors
- Harden test/disposable_backup_recovery_verification_test.dart with candidate path discovery and CI skip guard