fix(ghost): fix healthchecks for Ghost 6.x (301 redirects to external URL)

Ghost 6.x redirects all HTTP requests to the configured external URL.
- Docker healthcheck: use node http.get (accepts 301 as healthy)
- Controller probe: switch from api (expect 200) to http (any response)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

templates/ghost/.felhom.yml

@@ -56,8 +56,5 @@ app_info:
 # --- Controller-side health probe ---
 healthcheck:
   checks:
-    - type: api
+    - type: http
       port: 2368
-      path: "/ghost/api/v4/admin/site/"
-      expect:
-        status: 200