yangbear
98aeae4929
fix: 重连PageController和UIManager的FixationPanel按钮引用
修复原因：用户将BtnBack/BtnLimbFixation/BtnSplintFixation移入FixationPanel子物体后，
Inspector中的SerializeField引用自动断开，导致按钮点击无响应。
重连引用：
- _btnFixationBack → Canvas/FixationPanel/BtnBack
- _btnLimbFixation → Canvas/FixationPanel/BtnLimbFixation
- _btnSplintFixation → Canvas/FixationPanel/BtnSplintFixation
- _experimentPanel → Canvas/ExperimentPanel
- _btnExperimentBack → Canvas/ExperimentPanel/BtnBack
- UIManager._btnLimbFixation / _btnSplintFixation 同步重连