v0.4.3

Added

• argus_cortex.gpu: GPU tenancy shared across the stages, generalised
  from argus-lens's gpu coordinator.
  • GpuCoordinator: the protocol. lease(caller=, min_vram_mb=) is a
    context manager that holds a GPU slot for its body. GpuLeaseTimeout is a
    TimeoutError.
  • NullCoordinator: no gating, and the default.
  • LeaseCoordinator: an exclusive flock that every argus process on the
    host takes, then, while still holding it, a wait until free_vram_mb()
    reports min_vram_mb. Unlike lens's lease, min_vram_mb is honoured. NVML
    counts every process on the card, so ComfyUI and Ollama are accounted for
    without taking part. One deadline covers both waits. A probe that cannot
    run (no driver, no [gpu] extra, a CPU host) lets the lease through.
  • free_vram_mb(device): NVML free memory in MB, or None.
  • build_coordinator() / coordinator_from_env(): ARGUS_GPU_COORDINATOR
    (none / lease), ARGUS_GPU_LEASE_PATH, ARGUS_GPU_LEASE_TIMEOUT_S
    (300 s) and ARGUS_GPU_DEVICE. These are the names lens already reads. An
    unusable number logs a warning and falls back to the default.
  • The default lock is <tempdir>/argus-gpu.lock. Containers have their own
    /tmp, so a shared lock needs ARGUS_GPU_LEASE_PATH on a volume every
    GPU service mounts. The lock file is chmod 0o666 after create so a
    restrictive umask does not block other container UIDs from opening it.
• [gpu] extra: nvidia-ml-py, imported only when probed.