Fix: apply hf_ptq __main__ post-parse conversions (dataset split, calib_size int list)

When calling hf_main(args) directly, the __main__ block conversions that
run between parse_args() and main() are skipped. calib_size stays as
string '128' instead of [128], causing TypeError on list concatenation.

scripts/quantize_nvfp4.py

@@ -227,6 +227,12 @@ def run_calibration(model_path, export_dir, calib_save_path, amax_snapshot_path,
     args = parse_args()
     sys.argv = saved_argv
 
+    # Apply the same post-parse conversions that hf_ptq's __main__ block does
+    # (these normally run between parse_args() and main() in the original script,
+    # but since we call main() directly, we have to do them ourselves)
+    args.dataset = args.dataset.split(",") if isinstance(args.dataset, str) else args.dataset
+    args.calib_size = [int(num_sample) for num_sample in args.calib_size.split(",")]
+
     # ── Post-calibration hook ──
     # We monkey-patch export_quantized to add our defensive saves before export.
     import hf_ptq