Update progress.zig and integrate into sync command:
- progress.zig: update import from colors.zig to io.zig
- sync.zig: add ProgressBar for multi-run sync operations
- Shows progress bar when syncing 2+ runs (not in JSON mode)
- Updates progress after each successful sync
Benefits:
- Better UX for long-running sync operations
- Visual feedback on sync progress
- Maintains clean output for single runs
All tests pass.
Add progress reporting and offline sync infrastructure:
- progress.zig: progress bars and status reporting
- sync_manager.zig: offline run synchronization manager
Supports resilient operation with server connectivity issues.
