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/docker-compose.yml

@@ -26,7 +26,7 @@ services:
         limits:
           memory: 512M
     healthcheck:
-      test: ["CMD", "wget", "--spider", "-q", "http://localhost:2368/ghost/api/v4/admin/site/"]
+      test: ["CMD", "node", "-e", "require('http').get('http://localhost:2368/',r=>{process.exit(r.statusCode<400?0:1)}).on('error',()=>process.exit(1))"]
       interval: 30s
       timeout: 5s
       retries: 3