Add init container to Valkey to wait for Flannel CNI readiness

Prevents FailedCreatePodSandBox errors when talos-worker1 reboots and pods
try to start before Flannel writes /run/flannel/subnet.env.

Init container polls DNS resolution until network is ready before starting Valkey.

k8s/valkey-statefulset.yaml

@@ -23,6 +23,29 @@ spec:
         fsGroup: 999
         seccompProfile:
           type: RuntimeDefault
+      # Init container to wait for network to be ready (Flannel CNI)
+      initContainers:
+        - name: wait-for-network
+          image: busybox:1.36
+          command:
+            - sh
+            - -c
+            - |
+              echo "Waiting for network to be ready..."
+              until nslookup kubernetes.default.svc.cluster.local > /dev/null 2>&1; do
+                echo "Network not ready, retrying in 2s..."
+                sleep 2
+              done
+              echo "Network is ready!"
+          securityContext:
+            allowPrivilegeEscalation: false
+            runAsNonRoot: true
+            runAsUser: 999
+            capabilities:
+              drop:
+                - ALL
+            seccompProfile:
+              type: RuntimeDefault
       containers:
         - name: valkey
           image: valkey/valkey:8.0-alpine