feat: Implement search and filter functionality in MedTrackerApp

- Added DataFilter class for managing filtering and searching of medical data.
- Introduced SearchFilterWidget for UI controls related to search and filters.
- Integrated search and filter features into MedTrackerApp, allowing users to filter data by date range, medicine status, and pathology scores.
- Implemented quick filters for common use cases (last week, last month, high symptoms).
- Enhanced data loading and display logic to accommodate filtered data.
- Added error handling for data loading issues.
- Updated UIManager to reflect filter status in the application.
- Improved entry validation in add_new_entry method to ensure data integrity.

.gitignore

@@ -1,6 +1,7 @@
 # Data files (except example data)
 thechart_data.csv
 ### !thechart_data.csv
+backups/
 
 # Environment files
 .env