fix(platform): apply production hardening from audit plan

Close billing, tenancy, migration, build, and CI/CD gaps identified in the
audit: wallet/gateway guards, full-UUID namespaces, idempotent migrations with
base schema, stateful service stability, safer Dockerfiles/git builds, and
platform chart hardening (Redis auth, RollingUpdate, backups, Swagger off).

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/helm/cloudhost-app/values.yaml

@@ -101,3 +101,9 @@ changeCause: ""
 # ── Registry (for imagePullSecret) ──────────────────────
 registry:
   url: "localhost:30500"
+
+# ── Base images ──────────────────────────────────────────
+images:
+  # Optional mirror registry prefix for Docker Hub images (postgres, mysql,
+  # redis, rabbitmq, fluent-bit, …), e.g. "mirror.example.com".
+  baseRegistry: ""