fix: remove PVC patch that broke kubectl apply on bound claims

The mysql-data-pvc was already dynamically provisioned by the cluster's
'local-path' StorageClass. The overlay patch tried to change storageClassName
to 'manual' and volumeName on an already-bound PVC, which Kubernetes forbids:
  "spec is immutable after creation except resources.requests"

Fixes:
- Remove mysql-pvc-patch from kustomization.yaml (PVC left as-is)
- Remove mysql-pv.yaml resource (not needed with dynamic provisioner)
- Add comment explaining when manual PV/PVC is needed vs not

Jenkinsfile: add --timeout and FQDN to smoke test curl; add comments
explaining MySQL Recreate strategy startup timing expectations.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Jenkinsfile

@@ -115,11 +115,18 @@ pipeline {
                 withKubeConfig([credentialsId: "${K8S_CRED_ID}"]) {
                     sh "kubectl apply -k ${K8S_OVERLAY}"
 
+                    // MySQL uses Recreate strategy: old pod terminates (~30s) before
+                    // new pod starts. Readiness probe initialDelaySeconds=30 + up to
+                    // 10 retries × 5s = 80s. Total worst-case: ~110s → 300s is safe.
                     sh "kubectl rollout status deployment/mysql   -n scrum-manager --timeout=300s"
+
+                    // Backend initContainer sleeps 15s after MySQL TCP is up before
+                    // starting the Node process. 300s covers slow-start scenarios.
                     sh "kubectl rollout status deployment/backend  -n scrum-manager --timeout=300s"
+
                     sh "kubectl rollout status deployment/frontend -n scrum-manager --timeout=180s"
 
-                    echo "✅ All deployments rolled out."
+                    echo "All deployments rolled out."
                 }
             }
         }
@@ -127,14 +134,18 @@ pipeline {
         stage('Smoke Test') {
             steps {
                 withKubeConfig([credentialsId: "${K8S_CRED_ID}"]) {
+                    // Run a curl pod inside the cluster to hit the backend health endpoint.
+                    // Uses FQDN (backend.scrum-manager.svc.cluster.local) to be explicit.
                     sh """
                         kubectl run smoke-${BUILD_NUMBER} \
-                            --image=curlimages/curl:latest \
+                            --image=curlimages/curl:8.5.0 \
                             --restart=Never \
                             --rm \
                             --attach \
+                            --timeout=30s \
                             -n scrum-manager \
-                            -- curl -sf http://backend:3001/api/health \
+                            -- curl -sf --max-time 10 \
+                               http://backend.scrum-manager.svc.cluster.local:3001/api/health \
                         && echo "Health check PASSED" \
                         || echo "Health check FAILED (non-blocking)"
                     """