hf jobs: propagate TEST_ONLY env through launcher + remote runner

training: use -- and bash -c to bypass hf CLI typer flag stealing

training: default Space to ycwhencpp/final-iteration

training: split remote runner into in-repo script

update

training: default flavor a10g-largex4 (4xA10G, 96GB VRAM)

training: smoke-mode + hardcoded peak hint + valid tool IDs

train: default HF Job flavor l4x1 -> l40sx1 (48GB VRAM)

train: per-step credit + drop replies + larger batches

update