Upload train/preflight.py with huggingface_hub

Upload train/preflight.py with huggingface_hub

Upload train/preflight.py with huggingface_hub

train: preflight -- static-review fixes: absolute-step cursor, hub_listing pagination, cursor required on resume, repo_type everywhere, rank-0 repo create

preflight: P2 fast-fails after the first dead cell (each repeat bills a GPU session)

preflight: P2 parses RUN_JSON per cell and requires the frozen 22L/2048 cell to report

preflight: assert the trapezoid SHAPE (off-by-one at the last step is expected, not a bug)

train: preflight -- readback counts as verification; GQA kv must divide heads; pargs reports before optional probe

train: preflight -- download_checkpoint prefix/landing-dir fix (found by P1 v2)

preflight: stage pargs -- construct TrainingArguments/model/schedule on the Kaggle image, cross-check 22L=106,194,240 and 20L=99,114,048

train: preflight -- hubckpt.ensure_repo writes LFS attributes before the first checkpoint push (found by P1)

train: Gate 3 preflight driver (reader, hub cycle, T1 throughput, cold resume)