fix(k8s): allow relative paths for kind deployment PVs

Kind deployments can use relative paths because the extraMounts config
resolves them to absolute paths on the host. The PV creation should not
skip relative paths for kind deployments since the PV will use the
/mnt/<volume> path inside the kind node.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

stack_orchestrator/deploy/k8s/cluster_info.py

@@ -352,6 +352,8 @@ class ClusterInfo:
                 continue
 
             if not os.path.isabs(volume_path):
+                # Kind deployments allow relative paths (resolved via extraMounts)
+                if not self.spec.is_kind_deployment():
                     print(
                         f"WARNING: {volume_name}:{volume_path} is not absolute, "
                         "cannot bind volume."