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

ansible/roles/borgmatic/defaults/main.yml

@@ -41,17 +41,12 @@ borgmatic_keep_monthly: 12
 borgmatic_keep_yearly: 1000
 
 # PostgreSQL databases to backup (streamed via pg_dump)
-# Password is read from ~/.pgpass (managed by postgresql role)
+# Password is read from ~/.pgpass (managed by this role)
 # pg_dump_command must be full path since LaunchAgent doesn't have homebrew in PATH
 borgmatic_pg_dump_command: /opt/homebrew/opt/postgresql@18/bin/pg_dump
 borgmatic_postgresql_databases:
-  # Brew PostgreSQL on indri (current production)
+  # k8s PostgreSQL (CloudNativePG)
   - name: miniflux
-    hostname: localhost
-    port: 5432
-    username: borgmatic
-  # k8s PostgreSQL (CloudNativePG) - backup both during migration
-  - name: miniflux
-    hostname: k8s-pg.tail8d86e.ts.net
+    hostname: pg.tail8d86e.ts.net
     port: 5432
     username: borgmatic