fix(k8s): remove job-name label that conflicts with k8s auto-label

Kubernetes automatically adds a job-name label to Job pod templates
matching the full Job name. Our custom job-name label used the short
name, causing a 422 validation error. Let k8s manage this label.

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

stack_orchestrator/deploy/k8s/cluster_info.py

@@ -668,7 +668,7 @@ class ClusterInfo:
 
             template = client.V1PodTemplateSpec(
                 metadata=client.V1ObjectMeta(
-                    labels={"app": self.app_name, "job-name": job_name}
+                    labels={"app": self.app_name}
                 ),
                 spec=client.V1PodSpec(
                     containers=containers,