feat(k8s): namespace-per-deployment for resource isolation and cleanup

Each deployment now gets its own Kubernetes namespace (laconic-{deployment_id}).
This provides:
- Resource isolation between deployments on the same cluster
- Simplified cleanup: deleting the namespace cascades to all namespaced resources
- No orphaned resources possible when deployment IDs change

Changes:
- Set k8s_namespace based on deployment name in __init__
- Add _ensure_namespace() to create namespace before deploying resources
- Add _delete_namespace() for cleanup
- Simplify down() to just delete PVs (cluster-scoped) and the namespace
- Fix hardcoded "default" namespace in logs function

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

stack_orchestrator/deploy/spec.py

@@ -128,9 +128,6 @@ class Spec:
     def get_http_proxy(self):
         return self.obj.get(constants.network_key, {}).get(constants.http_proxy_key, [])
 
-    def get_acme_email(self):
-        return self.obj.get(constants.network_key, {}).get("acme-email", "")
-
     def get_annotations(self):
         return self.obj.get(constants.annotations_key, {})