Add Transmission metrics exporter and Grafana dashboard (#271)
## Summary
- Add `metalmatze/transmission-exporter` as a sidecar container in the torrent deployment, exposing Prometheus metrics on port 19091
- Add metrics port to the torrent service for Prometheus scraping
- Add Prometheus scrape job targeting the transmission exporter
- Create Grafana dashboard with:
- Overview stats (download/upload speed, active/total torrents)
- Transfer speed timeseries (download + upload over time)
- Transfer volume stats (total downloaded/uploaded in selected range)
- Per-torrent download and upload rate timeseries
- Per-torrent details table (ratio, uploaded, percent done)
## Deployment and Testing
- [ ] Sync ArgoCD `torrent` app from branch — verify exporter sidecar starts
- [ ] Verify exporter metrics: `kubectl exec` into pod, `curl localhost:19091/metrics`
- [ ] Verify Prometheus scrapes it: check targets at prometheus.ops.eblu.me
- [ ] Open Grafana, find "Transmission" dashboard, verify panels populate
- [ ] Sync ArgoCD `prometheus` app from branch
- [ ] Sync ArgoCD `grafana-config` app from branch
Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/271
Erich Blume
95c8424e62