docs(seedbox): add README for Transmission stack

seedbox/stacks/transmission/README.md

@@ -0,0 +1,52 @@
+# Transmission Stack
+
+BitTorrent client with web interface, accessible via Tailscale.
+
+## Access
+
+- **URL**: https://transmission.taila5ad8.ts.net
+- **Default credentials**: Set via `TRANSMISSION_USER` and `TRANSMISSION_PASS` secrets
+
+## Ports
+
+| Port | Protocol | Exposure | Description |
+|------|----------|----------|-------------|
+| 9091 | TCP | Tailscale only | WebUI |
+| 51413 | TCP/UDP | Public | BitTorrent peer port |
+
+## Volumes
+
+| Path in container | Host path | Description |
+|-------------------|-----------|-------------|
+| `/config` | Docker volume | Transmission configuration |
+| `/downloads` | `/srv/seedbox/downloads` | Download directory (local SSD) |
+| `/media` | `/mnt/media` | Media library (NFS) |
+
+## Configuration
+
+### Download Paths
+
+In Transmission settings:
+- **Download to**: `/downloads`
+- **Move completed to**: `/media/downloads` (optional)
+
+### Peer Port
+
+The peer port 51413 is exposed publicly for optimal seeding performance. Ensure your firewall/router allows this port.
+
+## Troubleshooting
+
+```bash
+# Check logs
+docker logs transmission
+
+# Check Tailscale sidecar
+docker exec ts-transmission tailscale status
+
+# Restart stack
+cd /srv/seedbox/stacks/transmission
+docker compose restart
+
+# Check WebUI is responding
+docker exec ts-transmission curl -s http://127.0.0.1:9091
+```