Add TeslaMate deployment for Tesla Model Y data logging (#47)

## Summary
- Add TeslaMate k8s deployment with Tailscale ingress at tesla.tail8d86e.ts.net
- Add teslamate user to CloudNativePG blumeops-pg cluster
- Add TeslaMate PostgreSQL datasource to Grafana
- Import 18 TeslaMate Grafana dashboards for charging, drives, efficiency, etc.
- Add teslamate database to borgmatic backup configuration

## Deployment and Testing
- [ ] Create 1Password items: "TeslaMate DB Password" and "TeslaMate Encryption Key"
- [ ] Apply database user secret: `op inject -i argocd/manifests/databases/secret-teslamate.yaml.tpl | kubectl apply -f -`
- [ ] Sync blumeops-pg: `argocd app sync blumeops-pg`
- [ ] Create teslamate database
- [ ] Apply teslamate secrets (encryption key, db connection)
- [ ] Apply Grafana datasource secret: `op inject -i argocd/manifests/grafana-config/secret-teslamate-datasource.yaml.tpl | kubectl apply -f -`
- [ ] Sync apps and teslamate: `argocd app sync apps teslamate grafana grafana-config`
- [ ] Complete Tesla API OAuth flow at https://tesla.tail8d86e.ts.net
- [ ] Verify data collection starts
- [ ] Verify Grafana dashboards show data

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

Reviewed-on: https://forge.tail8d86e.ts.net/eblume/blumeops/pulls/47

ansible/roles/borgmatic/defaults/main.yml

@@ -46,3 +46,7 @@ borgmatic_postgresql_databases:
     hostname: pg.tail8d86e.ts.net
     port: 5432
     username: borgmatic
+  - name: teslamate
+    hostname: pg.tail8d86e.ts.net
+    port: 5432
+    username: borgmatic