deploy(railiance): in-cluster STATE_HUB_URL; retire state-hub bridge

Point activity-core at state-hub.state-hub.svc.cluster.local and scale
actcore-state-hub-bridge to 0 after CUST-WP-0054 Phase 3 cutover.

k8s/railiance/20-runtime.yaml

@@ -10,7 +10,7 @@ data:
   TEMPORAL_HOST: actcore-temporal:7233
   TEMPORAL_NAMESPACE: default
   NATS_URL: nats://actcore-nats:4222
-  STATE_HUB_URL: http://actcore-state-hub-bridge:8000
+  STATE_HUB_URL: http://state-hub.state-hub.svc.cluster.local:8000
   LLM_CONNECT_URL: http://llm-connect.activity-core.svc.cluster.local:8080
   LLM_CONNECT_TIMEOUT_SECONDS: "300"
   REPO_SCOPING_URL: http://repo-scoping.repo-scoping.svc.cluster.local:8020
@@ -558,7 +558,7 @@ metadata:
     app.kubernetes.io/name: actcore-state-hub-bridge
     app.kubernetes.io/part-of: activity-core
 spec:
-  replicas: 1
+  replicas: 0
   selector:
     matchLabels:
       app.kubernetes.io/name: actcore-state-hub-bridge