refactor: rename all custom K8s components to hightower

Namespace, Temporal, router, PVCs, labels, and GHCR API image all
renamed from shannon-* to hightower-*. Upstream references preserved:
worker image (ghcr.io/farhoodliquor/shannon), .shannon/ dirs,
@shannon/worker package imports.

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

apps/cli/infra/k8s/workspaces-pvc.yaml

@@ -2,7 +2,7 @@ apiVersion: v1
 kind: PersistentVolumeClaim
 metadata:
   name: hightower-workspaces
-  namespace: shannon
+  namespace: hightower
 spec:
   accessModes:
     - ReadWriteMany