P4: Miniflux migration + PostgreSQL consolidation (#33)

## Summary
- Deploy miniflux in k8s via ArgoCD
- Expose via Tailscale Ingress at feed.tail8d86e.ts.net
- Retire brew PostgreSQL (no longer needed)
- Rename k8s-pg to pg (canonical hostname)
- Remove ansible miniflux and postgresql roles
- Update borgmatic to backup pg.tail8d86e.ts.net
- Update all zk documentation

## Deployment and Testing
- [x] Miniflux pod running in k8s
- [x] User login works at https://feed.tail8d86e.ts.net
- [x] Feeds and entries visible
- [x] brew miniflux and postgresql stopped
- [x] Tailscale services migrated (feed, pg)
- [x] zk documentation updated
- [x] Run ansible to apply role removals
- [ ] Verify borgmatic backup with new pg hostname

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

Reviewed-on: https://forge.tail8d86e.ts.net/eblume/blumeops/pulls/33

argocd/manifests/miniflux/kustomization.yaml

@@ -0,0 +1,9 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+namespace: miniflux
+
+resources:
+  - deployment.yaml
+  - service.yaml
+  - ingress-tailscale.yaml