mock单测与libcmavsdk原生库脱钩

conftest新增fake_mavsdk fixture打桩mavsdk.offboard设定点类型,
两组网关测试autouse启用。修复树莓派原生库符号缺失时纯mock测试误失败
(该问题在树莓派实测暴露: 348条全绿不依赖mavsdk原生库)

utils/tests/pod_bridge/px4_gateway_test.py

@@ -13,6 +13,12 @@ import pytest
 from pod_bridge.px4_gateway import OwnState, Px4Gateway, _enum_int
 
 
+@pytest.fixture(autouse=True)
+def _stub_mavsdk(fake_mavsdk):
+    """本模块全部用例与真实 libcmavsdk.so 脱钩(树莓派原生库符号缺失实测)。"""
+    return fake_mavsdk
+
+
 class FakeOffboard:
     def __init__(self):
         self.body = []