feat(stats): per-game hints used + lifetime moves and hint share

Store the hints a player used in each game, and add two lifetime tiles —
Moves and Hint share — to the statistics screen.

- per-game: game_players.hints_used now counts EVERY hint (allowance + wallet),
  not just the free allowance, so it is the seat's true total hints used this
  game. The allowance decision (used < HintsPerPlayer) and the hint badge values
  (hints_remaining / wallet_balance) are unchanged — the lobby hint-count fix does
  NOT regress; only the admin "hints used" column, which silently under-counted
  wallet hints, becomes accurate.
- account_stats gains two summed counters: moves (the player's plays — passes and
  exchanges excluded) and hints_used (every hint). Computed at game finish in
  buildStats over the same non-guest, non-honest-AI games as the rest of the stats.
- wire: StatsView gains moves + hints_used (trailing); gateway + UI codec + model;
  regen.
- ui: two tiles (Moves, Hint share = hints_used/moves, one-decimal % in the active
  locale); card order games·wins·draws·losses·moves·hint-share·best game·win-rate.
- docs: ARCHITECTURE §9 + baseline comment, FUNCTIONAL (+ru), UI_DESIGN.

Tests: TestHintPolicy (hints_used counts the wallet hint), TestGameLifecycleAndStats
(moves>0, hints=0), gateway stats round-trip, UI hintShare unit + codec + e2e.

docs/ARCHITECTURE.md

@@ -603,7 +603,10 @@ disguised robot stays indistinguishable from a person.
   non-guest accounts only — the finish-time recompute skips any `is_guest`
   seat): wins, losses, **draws**, max points in a game, and
   max points for a single **move** (which already folds in every word the move
-  formed plus the all-tiles bonus). A tie increments draws only; a resignation or
+  formed plus the all-tiles bonus); plus two summed counters — `moves` (the player's
+  plays, i.e. tile placements; passes and exchanges do not count) and `hints_used`
+  (every hint taken, allowance + wallet) — from which the screen derives the **hint
+  share** = hints_used / moves. A tie increments draws only; a resignation or
   timeout is a loss for the acting player. A companion table **`account_best_move`**
   (keyed by account **and variant**) keeps the highest-scoring single play **per
   variant** with the word itself: its main word as an ordered JSON array of tiles