Replace group prediction cards with a per-game table + group/date filters

Remove unused predictions loading in main entry point

Refactor predictions table: implement model predictions display and update layout

Consistent model names in leaderboard (drop parenthetical detail)

Leaderboard: earned-vs-possible view, gate group bonuses, fix group grid re-render

Light theme redesign, hide header bar, native leaderboard

add initial implementation of World Cup 2026 prediction game with scoring rules and data storage

update README.md for World Cup 2026 Prediction Game configuration

initial commit