v1.15.9: self-kill watchdog for wedged jobs (

ComfyUI can deadlock mid-job — observed on LTX, the tiled VideoVAE decode stalls on the first tile during dynamic-VRAM staging (GPU idle, uninterruptible via /interrupt; not length-dependent — 5s clips hang, 65s clips complete). The job then never completes or errors, so runPromptAndGetOutputs never returns, inFlight stays pinned, and with MAX_QUEUE_DEPTH=1 the replica is stuck at /ready 503 until manually restarted.