Port Shelem layout/engine, add history, fix card flashing and count desync

Layout & engine borrowed from Shelem: waiting-room menu with seat swap and
force-start, game menu with bar-to-bottom, escalating turn reminder, three
hand modes defaulting to fan on touch, card-count badges instead of card
backs, leave buttons inside phase overlays, version footer with tap-to-update.

Seats now run clockwise from the viewer (left = +1, across = +2, right = +3)
so play flows anti-clockwise on screen as the server advances it; the pass
exchange was flipped to match, otherwise "pass left" delivered to the right.

Game history: finished games are saved with a per-hand breakdown, readable
from the profile and shown on the end-of-hand and end-of-game screens.

Card flashing: the service worker precaches all 52 faces, each face is decoded
once into a template image, and the renderers reconcile against existing DOM
instead of rebuilding it, so card nodes and their images survive a re-render.

Card-count integrity: a seat can no longer put two cards into one trick, and
the server snapshots each trick start and rewinds to the last sound state if
the four hands ever drift apart.

Leaderboard: ranked by win rate with a 5-game minimum; below-threshold players
are listed unranked. Moon shots are now recorded instead of always zero, and
stat reads no longer create and persist a row per user on every request.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -82,4 +82,53 @@ git pull
 
 ## Data
 
-Game data (users, stats, config) is stored in `./data/` which is bind-mounted into the container. It persists across restarts and rebuilds.
+Game data is stored in `./data/`, bind-mounted into the container, and persists
+across restarts and rebuilds:
+
+| File | Contents |
+|---|---|
+| `users.json` | Local accounts (Hokm/Shelem accounts come from `SHARED_USERS_FILE`) |
+| `stats.json` | Per-player totals behind the profile and leaderboard |
+| `config.json` | Runtime config (e.g. whether signups are open) |
+| `history.json` | Finished games with their round-by-round breakdown |
+
+`history.json` keeps the most recent 2000 games. Games with a bot at the table
+are not recorded, so neither history nor the leaderboard counts them.
+
+## Game history
+
+Every finished all-human game is saved with the score each player picked up in
+each hand. Players reach it from **Profile → 📜 Game History**; tapping a game
+shows the final standings and a hand-by-hand table with a ruled-off totals row.
+The same breakdown appears on the end-of-hand and end-of-game screens, so the
+running scores are visible from the first hand onwards rather than only at the
+end.
+
+## Leaderboard
+
+Ranked by **win rate** — the percentage of finished games in which the player
+had the lowest score. A game that ends in a tie for lowest counts as a win for
+each tied player. Average score per game breaks ties in the ranking, and there
+*lower* is better, since Hearts scores are penalty points.
+
+A player needs **5 finished games** before they take a rank, so one lucky game
+can't top the board. Players below that are still listed underneath the ranking,
+unranked and dimmed, showing how many more games they need. Change
+`MIN_RANKED_GAMES` in `server.js` to adjust; the client reads the value back from
+`/api/config`, so the label follows automatically.
+
+Games with a bot at the table are not counted at all.
+
+## Card-count integrity
+
+Hearts games could previously end early if one seat somehow got two cards into a
+single trick: that player ran out while everyone else still held cards. The
+server now rejects a second card from a seat that has already played in the
+current trick, refuses cards that aren't in the player's hand, and puts nobody
+on turn while a trick is resolving.
+
+As a backstop, it snapshots the table at the start of every trick (only when all
+four hands are level) and re-checks the counts after each trick and at the end of
+each hand. If they have drifted apart it rewinds to that last sound snapshot,
+tells every client (they show a brief notice), and play resumes from the start of
+that trick.