Observability cleanup and k8s service monitoring (#43) (#43)

## Summary
- Remove stale `/opt/homebrew/var/loki` from borgmatic backup (Loki migrated to k8s)
- Add Alloy k8s DaemonSet for automatic pod log collection with auto-discovery
- Add blackbox probes for miniflux, kiwix, transmission, devpi, argocd
- Add transmission-exporter sidecar for full metrics (speed, torrent counts, ratios)
- Replace stale devpi dashboard with probe-based metrics (status, response time, uptime)
- Add unified "K8s Services Health" dashboard for service uptime/response monitoring

## Manual cleanup already performed
- Deleted stale textfile metrics on indri: `devpi.prom`, `transmission.prom`
- Deleted stale data directories on indri: `/opt/homebrew/var/loki/`, `/opt/homebrew/var/prometheus/`

## Deployment and Testing
- [x] Sync `apps` application to pick up new alloy-k8s app
- [x] Deploy alloy-k8s on feature branch: `argocd app set alloy-k8s --revision feature/observability-cleanup && argocd app sync alloy-k8s`
- [x] Deploy torrent on feature branch (for transmission exporter): `argocd app set torrent --revision feature/observability-cleanup && argocd app sync torrent`
- [x] Deploy prometheus on feature branch (for new scrape config): `argocd app set prometheus --revision feature/observability-cleanup && argocd app sync prometheus`
- [x] Deploy grafana-config on feature branch (for dashboards): `argocd app set grafana-config --revision feature/observability-cleanup && argocd app sync grafana-config`
- [x] Verify pod logs appear in Loki/Grafana
- [x] Verify transmission metrics appear in Prometheus
- [x] Verify service probe metrics appear in Prometheus
- [x] Run `mise run provision-indri -- --tags borgmatic` to update borgmatic config
- [ ] After merge, reset apps to main and resync

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: https://forge.tail8d86e.ts.net/eblume/blumeops/pulls/43

ansible/roles/borgmatic/defaults/main.yml

@@ -11,14 +11,12 @@ borgmatic_schedule_hour: 2
 borgmatic_schedule_minute: 0
 
 # Source directories to back up
-# NOTE: devpi removed - now hosted in k8s (PVC handles persistence)
 borgmatic_source_directories:
   - /Users/erichblume/code/personal/zk
   - /opt/homebrew/var/forgejo
   - /Users/erichblume/.config/borgmatic
   - /Users/erichblume/Documents
   - /Users/erichblume/Pictures
-  - /opt/homebrew/var/loki
 
 # Backup repository
 borgmatic_repositories: