feat: add internal cluster admin endpoints

.env.example

@@ -25,6 +25,8 @@ REDIS_ADDR=localhost:6379
 # Secrets
 # 32-byte key, base64 encoded. Replace locally.
 MASTER_KEY_BASE64=
+# Internal operator API token for /internal/* routes. Replace locally.
+OPERATOR_TOKEN=
 
 # Frontend
 VITE_API_BASE_URL=http://localhost:8080