ModelTranslator: document reducer default divergence (CLI quad vs bl_decimate collapse)

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

Tools/ModelTranslator/bl_decimate.py

@@ -512,6 +512,8 @@ def main():
     src, out_fbx, target = argv[0], argv[1], int(argv[2])
     unwrap_mode = argv[3] if len(argv) > 3 else "seam"
     overlap_tol = float(argv[4]) if len(argv) > 4 and argv[4] else UV_OVERLAP_TOL
+    # 直接调 bl_decimate 缺省用 collapse(安全确定性)；model_decimate CLI 默认 quad，
+    # 但总显式传第 6 位，故此兜底仅用于直接 Blender 调用，两者默认不同是有意为之
     reducer_arg = argv[5] if len(argv) > 5 else "collapse"
     warnings = []