fix: 堆叠报错

Co-authored-by: Copilot <copilot@github.com>

ginka/train_vq.py

@@ -174,12 +174,20 @@ def make_map_image(map_flat: torch.Tensor, tile_dict: dict) -> np.ndarray:
 
 
 def hstack_images(imgs: list, gap: int = 4, color=(255, 255, 255)) -> np.ndarray:
-    """将多张等高图片横向拼接，之间插入白色竖线。"""
-    H = imgs[0].shape[0]
-    vline = np.full((H, gap, 3), color, dtype=np.uint8)
-    result = imgs[0]
+    """将多张图片横向拼接，之间插入竖线；高度不一致时底部补齐背景色。"""
+    max_h = max(img.shape[0] for img in imgs)
+
+    def _pad_h(img):
+        dh = max_h - img.shape[0]
+        if dh == 0:
+            return img
+        pad = np.full((dh, img.shape[1], 3), color, dtype=np.uint8)
+        return np.concatenate([img, pad], axis=0)
+
+    vline = np.full((max_h, gap, 3), color, dtype=np.uint8)
+    result = _pad_h(imgs[0])
     for img in imgs[1:]:
-        result = np.concatenate([result, vline, img], axis=1)
+        result = np.concatenate([result, vline, _pad_h(img)], axis=1)
     return result