Fix Redis connection in production with startup probe and explicit 127.0.0.1

Changes:
- Added startupProbe to towerops container to allow up to 70s for startup
  (gives Valkey sidecar time to be ready)
- Changed REDIS_HOST from 'localhost' to '127.0.0.1' for explicit loopback
- Removed initialDelaySeconds from liveness/readiness probes (handled by startup)
- Added comment clarifying Redis connects to Valkey sidecar

This ensures the app waits for Valkey to be ready before accepting traffic.

k8s/deployment.yaml

@@ -84,8 +84,9 @@ spec:
                 secretKeyRef:
                   name: towerops-secrets
                   key: SECRET_KEY_BASE
+            # Redis connection to Valkey sidecar container (localhost because same pod)
             - name: REDIS_HOST
-              value: "localhost"
+              value: "127.0.0.1"
             - name: REDIS_PORT
               value: "6379"
           envFrom:
@@ -100,11 +101,18 @@ spec:
             limits:
               memory: "2Gi"
               cpu: "500m"
+          startupProbe:
+            httpGet:
+              path: /health
+              port: 4000
+            initialDelaySeconds: 10
+            periodSeconds: 5
+            timeoutSeconds: 3
+            failureThreshold: 12  # 10s + (12 * 5s) = 70s max startup time
           livenessProbe:
             httpGet:
               path: /health
               port: 4000
-            initialDelaySeconds: 30
             periodSeconds: 10
             timeoutSeconds: 3
             failureThreshold: 3
@@ -112,7 +120,6 @@ spec:
             httpGet:
               path: /health
               port: 4000
-            initialDelaySeconds: 5
             periodSeconds: 3
             timeoutSeconds: 2
             successThreshold: 1