feat(stats): best-move word, moves & hint-share, and a hint-count fix (#81)

The statistics screen gains real depth, plus a hint-count bug fix found along the way.

- Best move per variant: the screen shows the actual best-move word (drawn as game
  tiles; a wildcard shows its letter but no value), broken down by game variant, empty
  variants omitted. New account_best_move table, written at game finish.
- Moves & hint share: two new lifetime tiles — the player's play count and the share of
  plays that used a hint — from summed account_stats counters (moves, hints_used).
  Honest-AI games are excluded, like the rest of the stats.
- Hint-count fix: the in-game hint badge no longer goes stale across games. The global
  wallet now rides the wire apart from the per-game allowance (wallet_balance on
  StateView/HintResult/StatsView), so the client reads the live wallet rather than a
  per-game snapshot; game_players.hints_used now counts every hint (allowance + wallet),
  its true per-game total.
- Account merge: sums the new moves/hints_used counters and merges the per-variant best
  moves (higher score kept), which it previously dropped.
- Admin: the user card shows Moves and Hints used.
- UI polish: tab/label wording, game-over text, and e2e selectors hardened against label
  changes.

All wire additions are trailing (backward-compatible). Docs (ARCHITECTURE, FUNCTIONAL +ru,
UISN_DESIGN) updated in step.

docs/FUNCTIONAL.md

@@ -229,7 +229,12 @@ honest-AI practice game (a live game's export would leak the move journal; an AI
 game is throwaway). The client shares the `.gcg` file where the platform supports
 it, otherwise downloads it. Statistics (durable accounts only):
 wins, losses, draws, max points in a game, and max points for a single move (the
-best play, which already includes every word it formed plus the all-tiles bonus).
+best play, which already includes every word it formed plus the all-tiles bonus). It
+also shows the player's **move count** (their plays — passes and exchanges do not
+count) and their **hint share** (the percentage of those plays where a hint was taken).
+The best move is also broken down **per game variant**, showing the **word itself**
+drawn as game tiles (a wildcard shows its letter but no value) — one row per variant
+the player has played, omitting variants with no plays.
 A game that can no longer be continued — because a rule changed and an earlier
 move would now be illegal — is closed as a **draw** the moment someone opens it,
 never left stuck on an error: the move history shows an impersonal organizer note