refactor: optimize material deletion with exact code matching and database queries

- Change from fuzzy material name matching to exact material code matching
- Migrate from MaterialsTypeToBeDeleted to MaterialsToBeDeleted table
- Add should_delete_material() for on-demand database queries
- Remove in-memory material list loading to reduce memory footprint
- Update documentation to reflect new matching logic
- Remove main scripts from git tracking (contain user-specific config)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.gitignore

@@ -23,6 +23,12 @@ tests/
 config/user_settings.json
 nul
 
+# 主脚本（包含用户特定配置）
+main.py
+main_clean.py
+main_ui.py
+record.py
+
 # 环境变量
 .env
 .env.local