Server and admin endpoints

Server/admin endpoints are for deployment owners. Keep admintoken out of frontend code.

Endpoints

Endpoint	Auth	Use
`GET /server/ok`	none	Health check. Returns server-up message.
`POST /server/license`	`admintoken`	Verify license status and expiry information.
`GET /server/update`	`admintoken` query/header behavior in handler	Check or apply update behavior from update controller.

curl http://localhost:1337/server/ok

curl -X POST http://localhost:1337/server/license \
  -H "admintoken: YOUR_ADMIN_TOKEN"

The handler reads the admin token from the admintoken header.