USBPrinter no longer raises on init — the service starts and stays
running regardless of whether a printer is connected, reconnecting
automatically on demand.
Print jobs are now queued and batched: a 500ms collection window
groups consecutive labels into a single USB write, eliminating gaps
when printing multiple labels from InvenTree.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- TCP server exposing USB Brother QL printers on port 9100
- Supports all Brother QL series label printers
- Async architecture for handling concurrent print jobs
- Raspberry Pi deployment script and systemd service
- Documentation for setup and InvenTree integration