Fix widow/play bugs, exit-anywhere; rework leaderboard + add game history

- Widow: preserve card selection across re-renders (no more deselecting)
- Play: reject a second card during trick resolution (fixes hand-count desync)
- Leave: exit available during bidding/widow/trump; a mid-game leave hands the
  seat to AI so the game continues; rooms with no humans are torn down
- Leaderboard: one-time flush + schema migration, win rate as the primary
  ranking metric, per-team shelem and per-seat bid tracking, avg score + bids won
- History: per-game round-by-round records persisted to history.json, a history
  screen, and a vertical round breakdown (with totals) shown to all players at
  hand/game end; result held for 15s

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -8,4 +8,6 @@ data/
 node_modules/
 npm-debug.log*
 
-TODO
+TODO
+push.sh
+CLAUDE.md