feat: Implement application preferences with JSON persistence

- Added preferences management in `preferences.py` with functions to load, save, get, set, and reset preferences.
- Introduced a configuration directory structure based on the operating system.
- Integrated preferences into the settings window, allowing users to reset settings and manage window geometry.
- Enhanced `search_filter.py` to support flexible date column names and improved filtering logic.
- Updated `settings_window.py` to include options for managing backup and configuration folder paths.
- Introduced an `UndoManager` class to handle undo actions for add/update/delete operations.
- Improved UIManager to support sorting in tree views and added a toast notification feature.

docs/KEYBOARD_SHORTCUTS.md

@@ -6,6 +6,12 @@ TheChart application supports comprehensive keyboard shortcuts for improved prod
 - **Ctrl+S**: Save/Add new entry - Saves the current entry data to the database
 - **Ctrl+Q**: Quit application - Exits the application (with confirmation dialog)
 - **Ctrl+E**: Export data - Opens the export dialog window
+- **Ctrl+L**: Open logs folder - Opens the application logs directory in your file manager
+- **Ctrl+D**: Open data folder - Opens the data file's directory in your file manager
+- **Ctrl+B**: Open backups folder - Opens the backups directory in your file manager
+- **Ctrl+Shift+B**: Create backup now - Triggers a manual backup immediately
+ - **Ctrl+Shift+R**: Restore from backup - Choose a backup CSV to restore the data
+ - **Ctrl+Shift+C**: Open config folder - Opens the application configuration directory
 
 ## Data Management
 - **Ctrl+N**: Clear entries - Clears all input fields to start a new entry
@@ -23,6 +29,12 @@ TheChart application supports comprehensive keyboard shortcuts for improved prod
 
 ## Help
 - **F1**: Show keyboard shortcuts help - Displays a dialog with all available keyboard shortcuts
+- **Ctrl+H**: Open documentation - Opens the local docs directory or README in your default viewer
+
+## Notes
+- Opening Export or Settings shows a brief toast for confirmation.
+- Opening Logs/Data/Backups or Documentation shows a brief toast and a status message.
+ - Backup events also update a persistent "Last backup" indicator in the status bar.
 
 ## Implementation Details
 
@@ -54,6 +66,7 @@ Primary action buttons show their keyboard shortcuts in the button text (e.g., "
 2. Enter data in the form
 3. **Ctrl+S** - Save the entry
 4. **F5** - Refresh to see updated data
+5. **Ctrl+L** - Open logs folder to inspect logs if something went wrong
 
 ### Navigation
 - Use **Ctrl+M** and **Ctrl+P** to quickly access management windows