feat(cli): time --tz 时区偏移（默认本机时区的修正项），151 测试全绿

tests/test_cli.py

@@ -286,3 +286,17 @@ class TestViaBridge:
         code, _ = run_cli(capsys, ["--json", "scan"])
         assert code == 0
         assert called["args"] == ("10.0.0.7", 8971)
+
+
+class TestTimeTz:
+    def test_tz_offset_applied(self, capsys, monkeypatch):
+        """--tz 8 应写入北京墙钟（与系统 UTC 本地时相差 8h）"""
+        import datetime as _dt
+        code, out = run_cli(capsys, ["--json", "time", "--tz", "8"])
+        assert code == 0
+        sent = FakeTransport.instances[0].rxtx_writes[0]
+        # dd 帧的 unix 字段（本地墙钟按 UTC 计）反解小时
+        unix_local = int.from_bytes(sent[1:5], "big")
+        wall = _dt.datetime.fromtimestamp(unix_local, _dt.timezone.utc)
+        utc_now = _dt.datetime.now(_dt.timezone.utc)
+        assert abs((wall - utc_now).total_seconds() - 8 * 3600) < 120