feat(platform): Add connections (signal-cli-rest-api) service

- Deploy signal-cli-rest-api 0.85 for Hermes Signal notifications
- Replace broken astro-orbiter VM (10.1.71.130:8080) with K8s service
- ArgoCD-managed GitOps deployment in connections namespace
- NFS-backed persistent storage for signal-cli state
- Fixes UNREGISTERED_FAILURE affecting midday market cron job
- Epcot-themed service (communication pavilion concept)

Service endpoint: http://connections.connections.svc.cluster.local:8080

cluster/platform/connections/persistentvolumeclaim.yaml

@@ -0,0 +1,16 @@
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: signal-cli-data
+  namespace: connections
+  labels:
+    app.kubernetes.io/name: connections
+    app.kubernetes.io/component: storage
+spec:
+  accessModes:
+    - ReadWriteOnce
+  storageClassName: nfs-emporium  # NFS CSI storage class
+  resources:
+    requests:
+      storage: 2Gi  # signal-cli state is small, 2Gi provides headroom
+  volumeMode: Filesystem