docs(runbooks): pgdb ops runbooks — health / restore / update + facts refresh (W1N-228)

- runbooks/pgdb-health.md: read-only health check (8 diagnostics) — containers,
  PG core + HA clients, write activity, TimescaleDB hypertables/compression,
  pgweb auth/bookmarks, daily custom-format backups, disk/fstab, logs
- runbooks/pgdb-restore.md: procedure-type restore (pg_restore -Fc, temp-DB swap,
  approval gates, rollback) — precondition command verified live
- runbooks/pgdb-update.md: gated command reference (pull -> config -q -> up -> verify;
  rollback = /opt/database/run + old volumes)
- index + validate-repo.sh classification updated; hosts/pgdb.md refreshed
  (SSH key auth works, scribe events hypertable, runbook cross-refs)

runbooks/README.md

@@ -16,6 +16,9 @@ runbooks start from [`_template.md`](_template.md).
 | PowerDNS health check | [pdns-health.md](pdns-health.md) | read-only |
 | RustDesk health check | [rustdesk-health.md](rustdesk-health.md) | read-only |
 | Matrix health check | [matrix-health.md](matrix-health.md) | read-only |
+| pgdb health check | [pgdb-health.md](pgdb-health.md) | read-only |
+| pgdb DB restore (pg_restore) | [pgdb-restore.md](pgdb-restore.md) | change (procedure) |
+| pgdb image/compose update | [pgdb-update.md](pgdb-update.md) | change (gated) |
 | AdGuard Home health check | [adguard-home-health.md](adguard-home-health.md) | read-only |
 | Matter packet capture | [matter-packet-capture.md](matter-packet-capture.md) | read-only |
 | Home Assistant maintenance | [home-assistant-maintenance.md](home-assistant-maintenance.md) | change (gated) |