[Copilot]

JobController::retryAfter() recorded a delay but returned the controller, so it could not be used to stop job execution with throw. It now returns a dedicated retry signal that middleware handles without treating the job as failed.

• Usage: Throw the returned signal to stop the job immediately; calls without throw continue to record the retry delay.

  throw $controller->retryAfter(30);

• Handling: Middleware captures the signal and preserves the retry delay without marking the job failed.
• Coverage: Added a regression test for stopping job execution with a retry signal.

• Fixes [Queue] $controller->retryAfter(30) cannot throw #1373