v0.7.1

Fixed

• A GPU that is too small no longer reads as "GPU busy". A user with a 2 GB
  laptop card reported the pipeline "stuck": gpu_check.py compared free VRAM
  against --min-free-mb 6000, said blocked — wait for other tasks, and the
  skill instructions say not to retry. Nothing was going to free up — the card
  cannot hold a large-v3-class model at all. The pre-flight now checks total
  VRAM first and, when the card can never pass, prints GPU_TOO_SMALL with the
  three real options (CPU path, --model small, --engine groq) and exits 0,
  the same verdict as "no NVIDIA card". --require-gpu keeps the hard block for
  batch hosts that must not silently run on CPU.
• Load-time CUDA OOM falls back to CPU explicitly. The fallback used to fire
  only because the OOM text happened to contain the word cuda; it is now a
  recognised case with its own message ("the card is too small for this model")
  and log reason, in both transcribe_video.py and the collapse-retry child.
• The collapse-retry child no longer re-attempts CUDA after the parent already
  fell back. transcribe_video.py exports LECTURE_ASR_DEVICE=cpu once it is
  on CPU; retranscribe_segment.py honours it instead of OOM-ing a second time.

Added

• transcribe_video.py --device {auto,cuda,cpu}. auto (default) is the
  existing behaviour; cpu skips the CUDA attempt and prints the ETA up front
  (pair with --model small/medium on 2–4 GB machines); cuda never falls
  back and fails loudly.
• README (both languages): a small GPU (2–4 GB) counts as no GPU — which flags to
  use and which optional stages to skip.

Changed (synced from upstream, no user-facing behaviour on other machines)

• GPU stages take a machine-wide FIFO lease when the author's gpu_lease.py is
  present next to the skill; on any other machine gpu_lease_ctx() is a
  no-op. Replaces the older best-effort pause-flag wait in transcribe_video.py,
  vlm_signals.py, retranscribe_segment.py, ocr_surya.py.
• batch/build_L1.py: a deck-only (unrecorded) slide keeps up to 24 text lines
  in L1 instead of the 6 a video frame gets — the deck text is the only content
  there.