feat: --retry -1 无限次自动补传

tests/test_transfer.py

@@ -366,3 +366,7 @@ def test_count_files_only_files(tmp_path):
     (tmp_path / "a.txt").write_text("x")
     (tmp_path / "dir1").mkdir()
     assert transfer.count_files(str(tmp_path)) == 1  # 目录不计
+
+def test_parse_args_retry_infinite():
+    args = transfer.parse_args(["--retry", "-1", "s", "d"])
+    assert args.retry == -1  # 无限重试