fix: 终极状态回滚 + 三个 panel 短路径导包修复

- water_quality_gui_v2.py：回滚机制由 panel_registry.get_tab_index 改为基于 PANEL_REGISTRY[current_tab_idx]['step_id'] 的索引反查，消除不存在的 get_tab_index 导致回滚期间二次崩溃并被静默吞噬的幽灵跳步根因

src/gui/water_quality_gui_v2.py

@@ -482,22 +482,20 @@ class WaterQualityGUI(QMainWindow):
             QMessageBox.critical(self, "面板加载失败",
                                  f"加载页面时发生严重错误：\n{e}\n\n详见终端日志。")
 
-            # ====== 新增：状态回滚（解决幽灵跳转/假死） ======
-            # 既然右侧未能成功切换，必须强制将左侧导航栏的选中项退回到与右侧一致
+            # ====== 终极状态回滚机制 ======
             self._step_list.blockSignals(True)
             try:
                 current_tab_idx = self._tab_widget.currentIndex()
-                from src.gui.core.panel_registry import get_tab_index
-                # 遍历左侧列表，找到属于当前显示的 tab_index 的那个 step
-                for i in range(self._step_list.count()):
-                    item_node = self._step_list.item(i)
-                    if item_node:
-                        node_data = item_node.data(Qt.UserRole)
-                        if node_data and node_data != "stage_header" and get_tab_index(node_data) == current_tab_idx:
+                from src.gui.core.panel_registry import PANEL_REGISTRY
+                if 0 <= current_tab_idx < len(PANEL_REGISTRY):
+                    correct_step_id = PANEL_REGISTRY[current_tab_idx]['step_id']
+                    for i in range(self._step_list.count()):
+                        item_node = self._step_list.item(i)
+                        if item_node and item_node.data(Qt.UserRole) == correct_step_id:
                             self._step_list.setCurrentRow(i)
                             break
             except Exception:
-                pass  # 回滚期间如果发生异常，默默忽略，防止二次崩溃
+                pass
             finally:
                 self._step_list.blockSignals(False)