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.

ui/src/lib/gamedelta.test.ts

@@ -27,7 +27,7 @@ function move(player: number): MoveRecord {
 }
 
 function cache(moveCount: number, seat = 0, over = false): CachedGame {
-  const view: StateView = { game: gameView(moveCount, over), seat, rack: ['a', 'b'], bagLen: 50, hintsRemaining: 1 };
+  const view: StateView = { game: gameView(moveCount, over), seat, rack: ['a', 'b'], bagLen: 50, hintsRemaining: 1, walletBalance: 0 };
   return { view, moves: [] };
 }
 
@@ -37,7 +37,7 @@ function delta(moveCount: number, player: number, bagLen = 47): MoveDelta {
 
 describe('seedInitialState', () => {
   it('wraps an initial view with an empty journal', () => {
-    const view: StateView = { game: gameView(0), seat: 1, rack: ['x'], bagLen: 80, hintsRemaining: 2 };
+    const view: StateView = { game: gameView(0), seat: 1, rack: ['x'], bagLen: 80, hintsRemaining: 2, walletBalance: 0 };
     expect(seedInitialState(view)).toEqual({ view, moves: [] });
   });
 });
@@ -152,12 +152,12 @@ describe('applyOpponentJoined', () => {
       { seat: 0, accountId: 'me', displayName: 'Me', score: 0, hintsUsed: 0, isWinner: false },
       { seat: 1, accountId: 'opp', displayName: 'Opp', score: 0, hintsUsed: 0, isWinner: false },
     ] };
-    return { game, seat: 0, rack: ['x'], bagLen: 90, hintsRemaining: 0 };
+    return { game, seat: 0, rack: ['x'], bagLen: 90, hintsRemaining: 0, walletBalance: 0 };
   }
 
   it("adopts the joined seats and status while preserving the cached rack and moves", () => {
     // The cached open game is still "searching": empty seats, status open, the starter's own rack.
-    const cached: CachedGame = { view: { game: { ...gameView(2), status: 'open', seats: [] }, seat: 0, rack: ['a', 'b'], bagLen: 50, hintsRemaining: 1 }, moves: [move(0)] };
+    const cached: CachedGame = { view: { game: { ...gameView(2), status: 'open', seats: [] }, seat: 0, rack: ['a', 'b'], bagLen: 50, hintsRemaining: 1, walletBalance: 0 }, moves: [move(0)] };
     const res = applyOpponentJoined(cached, joinedState());
     expect(res?.view.game.status).toBe('active');
     expect(res?.view.game.seats).toHaveLength(2);