Update HF Jobs training script

scripts/hf_jobs_train_syllabus.py

@@ -44,8 +44,21 @@ def run(cmd: list[str], *, cwd: Path | None = None) -> None:
     subprocess.run(cmd, check=True, cwd=cwd)
 
 
+def _require_hub_token() -> str:
+    token = os.environ.get("HF_TOKEN", "").strip()
+    if not token or token in ("$HF_TOKEN", "${HF_TOKEN}"):
+        raise SystemExit(
+            "HF_TOKEN is missing or still the literal '$HF_TOKEN' placeholder.\n"
+            "Resubmit with: uv run python scripts/submit_hf_training_job.py\n"
+            "Or CLI: hf jobs uv run --secrets HF_TOKEN <script-url>\n"
+            "(Do not pass secrets={'HF_TOKEN': '$HF_TOKEN'} from Python — use the real token.)"
+        )
+    return token
+
+
 def main() -> None:
-    api = HfApi()
+    token = _require_hub_token()
+    api = HfApi(token=token)
     who = api.whoami()["name"]
     print(f"Hub user: {who}")
     print(f"Dataset: {DATASET_REPO}")