refactor: rename custom components from shannon-* to hightower-*

Renames API server, worker jobs, credentials secret, and workspaces
PVC to use the hightower prefix. Upstream Shannon names (namespace,
Temporal service, package imports, .shannon/ dir) are unchanged.

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

apps/api/infra/overlays/dev/kustomization.yaml

@@ -7,7 +7,7 @@ patches:
       apiVersion: apps/v1
       kind: Deployment
       metadata:
-        name: shannon-api
+        name: hightower-api
       spec:
         template:
           spec: