fix(job_train): pip install huggingface_hub before downloading data files (R1 parity with job_smoke.sh)

scripts/job_train.sh

@@ -5,6 +5,9 @@ set -e
 cd /w
 export PYTHONPATH="/w:${PYTHONPATH}"
 
+# Install huggingface_hub first so we can download data files (parity with job_smoke.sh)
+pip install -q 'huggingface_hub>=0.28'
+
 # Fetch large data files from HF (uploaded separately via hf upload)
 mkdir -p data
 python -c "from huggingface_hub import hf_hub_download; [hf_hub_download(repo_id='Pratham-math/fathom-code', filename=f'data/{f}', local_dir='/w', token='${HF_TOKEN}') for f in ['train.jsonl','eval.jsonl','sft_traces.jsonl']]"