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/application.yaml

@@ -0,0 +1,35 @@
+# ------------------------------------------------------------------------------
+# Platform: connections (Signal Gateway)
+# Theme: epcot-connections (EPCOT: Communication & World Showcase)
+# Wave 8 — Signal-cli REST API for Hermes notifications
+# ------------------------------------------------------------------------------
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: connections
+  namespace: argocd
+  annotations:
+    argocd.argoproj.io/sync-wave: "8"
+spec:
+  project: default
+  source:
+    repoURL: https://gitea.mk-labs.cloud/rblundon/homelab.git
+    targetRevision: main
+    path: cluster/platform/connections
+    directory:
+      exclude: "application.yaml"
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: connections
+  syncPolicy:
+    automated:
+      prune: true
+      selfHeal: true
+    syncOptions:
+      - CreateNamespace=true
+    retry:
+      limit: 5
+      backoff:
+        duration: 5s
+        factor: 2
+        maxDuration: 3m

cluster/platform/connections/deployment.yaml

@@ -0,0 +1,67 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: connections
+  namespace: connections
+  labels:
+    app.kubernetes.io/name: connections
+    app.kubernetes.io/component: messaging-gateway
+    app.kubernetes.io/version: "0.85"  # Pin version initially
+spec:
+  replicas: 1  # MUST be 1 - signal-cli state is not multi-instance safe
+  strategy:
+    type: Recreate  # Prevents dual mount of PVC
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: connections
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: connections
+        app.kubernetes.io/component: messaging-gateway
+    spec:
+      securityContext:
+        fsGroup: 1000
+        runAsUser: 1000
+        runAsNonRoot: true
+      containers:
+      - name: signal-cli-rest-api
+        image: bbernhard/signal-cli-rest-api:0.85  # Pin version, test upgrades
+        imagePullPolicy: IfNotPresent
+        ports:
+        - containerPort: 8080
+          name: http
+          protocol: TCP
+        env:
+        - name: MODE
+          value: "json-rpc"  # json-rpc mode for API compatibility
+        volumeMounts:
+        - name: signal-data
+          mountPath: /home/.local/share/signal-cli
+        resources:
+          requests:
+            memory: "256Mi"
+            cpu: "100m"
+          limits:
+            memory: "512Mi"
+            cpu: "500m"
+        livenessProbe:
+          httpGet:
+            path: /v1/health
+            port: 8080
+          initialDelaySeconds: 30
+          periodSeconds: 10
+          timeoutSeconds: 5
+          failureThreshold: 3
+        readinessProbe:
+          httpGet:
+            path: /v1/health
+            port: 8080
+          initialDelaySeconds: 10
+          periodSeconds: 5
+          timeoutSeconds: 3
+          failureThreshold: 2
+      volumes:
+      - name: signal-data
+        persistentVolumeClaim:
+          claimName: signal-cli-data

cluster/platform/connections/namespace.yaml

@@ -0,0 +1,8 @@
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: connections
+  labels:
+    app.kubernetes.io/name: connections
+    app.kubernetes.io/component: messaging-gateway
+    theme: epcot

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

cluster/platform/connections/service.yaml

@@ -0,0 +1,17 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: connections
+  namespace: connections
+  labels:
+    app.kubernetes.io/name: connections
+    app.kubernetes.io/component: messaging-gateway
+spec:
+  type: ClusterIP
+  ports:
+  - port: 8080
+    targetPort: 8080
+    protocol: TCP
+    name: http
+  selector:
+    app.kubernetes.io/name: connections