在单位回退时就近提示缺少可用标定

让实时和回放的原始单位回退原因出现在力曲线单位按钮旁。相关定向测试与 lint gate 通过。

apps/studio/tests/test_replay_controller.py

@@ -111,6 +111,7 @@ class _Charts:
         self.followed = 0
         self.shown = 0
         self.cleared = 0
+        self.unit_fallbacks = 0
 
     def unit(self) -> str:
         return self._unit
@@ -134,6 +135,9 @@ class _Charts:
     def show_all(self) -> None:
         self.shown += 1
 
+    def show_unit_fallback(self) -> None:
+        self.unit_fallbacks += 1
+
 
 class _ImagePanel:
     def __init__(self) -> None:
@@ -584,6 +588,7 @@ def test_the_charts_fall_back_to_raw_when_a_recording_has_no_newtons(qt_app):
     assert engine.units[-1] == "raw"
     assert host.units[-1] == "raw"
     assert t("status.units_raw_fallback") in host.notes
+    assert parts[1].unit_fallbacks == 1
 
     engine._reader = _Reader(newtons=[1.0, 2.0, 3.0])
     controller.apply_source(True)