Nova polozka menu Rebricek a stranka /leaderboard: top 10 podla najlepsej hry (hry len s ludmi / s aspon jednym botom) a podla hodin v hre (hry do 3 h). Backend api/leaderboard.py + socket udalost get_leaderboard, testy v tests/test_history.py.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019YzEAACE9VgnLtXPuWGjwy
