Apply ruff format across the codebase

Whitespace-only reflow (line wrapping, blank lines between defs); no
logic changes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

giant/data/loader.py

@@ -60,9 +60,7 @@ def _pad_list_col_int(series: pd.Series, K: int, fill: int = 0) -> np.ndarray:
     return out
 
 
-def _pad_dir_col(
-    dx: pd.Series, dy: pd.Series, dz: pd.Series, K: int
-) -> np.ndarray:
+def _pad_dir_col(dx: pd.Series, dy: pd.Series, dz: pd.Series, K: int) -> np.ndarray:
     """Pad three list-valued direction columns → (N, K, 3) float32.
 
     Padding direction defaults to (0,0,1) (forward) so it is a valid unit vector.