fix: use maxSurge=0 rolling update to avoid CPU pressure on small cluster

During rolling updates with the default maxSurge=1, an extra surge pod was
created temporarily (3 pods instead of 2), causing all 3 nodes to report
"Insufficient CPU" and delaying scheduling past the Jenkins rollout timeout.

With maxSurge=0 / maxUnavailable=1, one old pod terminates first before a
new one starts — pod count stays at 2 throughout, no extra CPU needed.

Also increase Jenkins rollout timeout from 300s to 600s as a safety net
for CPU-constrained nodes that may still need extra scheduling time.

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

Jenkinsfile

@@ -137,16 +137,14 @@ pipeline {
                     // Show pod state immediately after apply so we can see pull/init status in logs
                     sh "kubectl get pods -n scrum-manager -o wide"
 
-                    // 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.
+                    // MySQL uses Recreate strategy: old pod terminates then new starts.
                     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. 512Mi memory limit avoids OOMKill.
-                    sh "kubectl rollout status deployment/backend  -n scrum-manager --timeout=300s"
+                    // maxSurge=0: old pod terminates first, new pod starts after.
+                    // CPU-constrained nodes may delay scheduling — 600s covers this.
+                    sh "kubectl rollout status deployment/backend  -n scrum-manager --timeout=600s"
 
-                    sh "kubectl rollout status deployment/frontend -n scrum-manager --timeout=180s"
+                    sh "kubectl rollout status deployment/frontend -n scrum-manager --timeout=600s"
 
                     echo "All deployments rolled out."
                 }