修复所有 Panel 的相对路径传递问题，防止 FileNotFoundError

src/gui/panels/step6_5_panel.py

@@ -230,6 +230,9 @@ class Step6_5Panel(QWidget):
         if main_window and hasattr(main_window, 'step5_panel'):
             step5_output_path = main_window.step5_panel.output_file.get_path()
             if step5_output_path:
+                # 若为相对路径，使用 work_dir 合成为绝对路径
+                if not os.path.isabs(step5_output_path):
+                    step5_output_path = os.path.join(self.work_dir or '', step5_output_path).replace('\\', '/')
                 existing = self.training_csv_file.get_path()
                 if not existing or not existing.strip():
                     self.training_csv_file.set_path(step5_output_path)