Record Core Hub lease and network readiness

docs/evidence/core-hub-shadow-preflight-2026-08-20.md

@@ -18,6 +18,13 @@ At `2026-08-20T21:31:13Z` on railiance01:
 - the KV store, database store and three ExternalSecret manifests all passed
   Kubernetes server-side dry-run after namespace creation.
 
+A disposable `postgres:16-alpine` pod was then allowed to become Ready in the
+`core-hub` namespace. DNS resolved
+`platform-pg-rw.databases.svc.cluster.local` to its ClusterIP and `pg_isready`
+reported port 5432 accepting connections. The probe used no database
+credential and was deleted immediately afterward. This verifies the reviewed
+namespace label and `platform-pg` consumer NetworkPolicy path.
+
 ## Source snapshot inventory
 
 A read-only query ran through the existing `coulombcore` SSH route against