feat(pgpool): implement WP-0003 T01-T04 — permanent fix for pgpool-password bug

T01: helm/gitea-values.yaml with postgresql-ha.pgpool.adminPassword
     (fill REPLACE_WITH_PGPOOL_ADMIN_PASSWORD before helm upgrade)
T02: tests/smoke_kube.sh — add pgpool and postgresql-ha pod health checks
T03: tests/test_ha_failover.sh — D3 HA failover test script
T04: docs/incidents/2026-03-10-pgpool-missing-secret.md + README link

Also: make test-ha-failover target, Makefile .PHONY updated.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/README.md

@@ -67,6 +67,10 @@ From two bare Linux servers, a Git repo, and valid credentials, you can rebuild
 4. **Deploy services**
    Install baseline services via Helm from the helm/ directory.
 
+## Incidents
+
+- [2026-03-10 — pgpool CrashLoopBackOff on PostgreSQL HA failover](incidents/2026-03-10-pgpool-missing-secret.md)
+
 ## 👥 Contributing
 
 See CONTRIBUTING.md for rules, coding style, and workflow.