fix: rename registry secret to image-pull-secret

The secret name `{app}-registry` is ambiguous — it could be a container
registry credential or a Laconic registry config. Rename to
`{app}-image-pull-secret` which clearly describes its purpose as a
Kubernetes imagePullSecret for private container registries.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

stack_orchestrator/deploy/deployment_create.py

@@ -620,7 +620,7 @@ def create_registry_secret(spec: Spec, deployment_name: str) -> Optional[str]:
     }
 
     # Secret name derived from deployment name
-    secret_name = f"{deployment_name}-registry"
+    secret_name = f"{deployment_name}-image-pull-secret"
 
     # Load kube config
     try: