firmware: avoid Arduino degrees macro collision

tests/test_xiao_sensor_node_contract.py

@@ -21,7 +21,11 @@ def test_loop_is_non_blocking():
     assert "updateGps" in loop and "updateImu" in loop and "TELEMETRY_INTERVAL_MS" in loop
     assert not re.search(r"delay\((?:[2-9]|[1-9]\d+)\)", loop)
 
+def test_imu_does_not_redeclare_arduino_degrees_macro():
+    imu = source("imu.cpp")
+    assert "float degrees(" not in imu
+    assert "radiansToDegrees" in imu
+
 def test_node_does_not_take_cargo_or_ble_authority():
     combined = "\n".join(p.read_text() for p in NODE.glob("*.*"))
     assert "NimBLE" not in combined and "JBD" not in combined and "server.on(" not in combined
-