fix: auto-save report after clean() completes in GUI and CLI

- Add save_report parameter to DiscreteMaterialPlanCleaner (default True)
- Auto-save report at end of clean() method when save_report_enabled
- Remove explicit save_report() call from main() (now automatic)
- Pass save_report=True in GUI _delete_worker()

This ensures reports are saved for both GUI and CLI execution paths.

Co-Authored-By: Claude (glm-5) <noreply@anthropic.com>

gui/material_validation_tab.py

@@ -1530,6 +1530,7 @@ class MaterialValidationTab(BaseTab):
                 headless=self.config.get("erp.headless", True),
                 verbose=True,
                 dryrun=dryrun,
+                save_report=True,
                 progress_callback=progress_callback,
             )