- Implemented automatic pruning of stale packages across all platform sync endpoints (Arch, AUR, Debian, Ubuntu, Fedora, Homebrew, Winget)
- Added `last_seen_at` tracking to mark packages as seen during sync runs and identify inactive packages
- Introduced `PRUNE_GRACE_DAYS` and `PRUNE_HARD_DELETE_DAYS` environment variables for configurable soft-delete and hard-delete thresholds
- Implemented SyncAuth to control sync access with server-only mode and secret key authorization
- Consolidated environment variables into single .env.example with improved sync configuration
- Protected all sync API endpoints (ubuntu, fedora, arch, homebrew, winget) with authentication checks