feat: add delete execution feature with progress tracking and dryrun mode

- Add ExecutionConfig for dryrun settings in config schema
- Create DeleteProgressWindow widget for real-time progress display
- Integrate delete execution flow in MaterialValidationTab with threading
- Add dryrun checkbox for admin users in settings
- Add progress callback support to DiscreteMaterialPlanCleaner
- Add markdown report generation with statistics
- Include tkinterweb and markdown2 dependencies for report rendering

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

requirements.txt

@@ -20,3 +20,7 @@ python-dateutil>=2.8.0
 pytz>=2023.0
 python-dotenv>=1.0.0
 tklinenums>=1.7.0
+
+# --- Markdown Rendering ---
+markdown2>=2.4.0
+tkinterweb>=3.23