* feat: add kill count tracking and table editing
- Add ItemDataV2 with optional killcount field
- Automatic data migration from legacy format with backup creation
- Config options to show killcount/date in details table
- Config option to enable/disable kill count input field
- Double click any row to edit entry element
- Right click -> context menu to edit entire entry
- Separation of concerns for more maintainable code
- Enhanced tooltips
- Remove unused legacy code (ItemEntry, duplicate ImageRenderer)
- Cleaned up unused ColorScheme constants
* refactor: replace java.util.logging with Slf4j and downgrade info logs to debug
