Added CLAUDE.md to document coding style:
- Use final declarations where possible
- No early returns (avoid guard clauses)
- No extra empty lines in method bodies
Applied style fixes to LeaderboardPanel:
- Removed early return in selectionChangeHandler, inverted condition instead
- Added final to all local variables and parameters
- Removed extra empty line in addedToSelection/removedFromSelection
- Moved guard flag setting inside condition in updateSelection to avoid unnecessary flag toggling
Axel Uhl