fix(game): show granted/bought hints in-game — finish the D31 wire removal

The in-game hint badge ignored the payments hint wallet: loading a game clobbered
app.profile.hintBalance with the deprecated StateView.wallet_balance (zeroed in the
D31 domain removal but left in the protocol as a dead 0, then synced over the real
balance at game load).

Finish the removal honestly. StateView carries the per-game allowance alone
(hints_remaining); the purchasable wallet lives solely on the profile and the client
adds it (lib/hints). Removed StateView.wallet_balance across every layer — backend
StateView/DTO, notify.PlayerState (live events), gateway StateResp + wire.StateView,
the client model/codec/mock/localgame — and dropped the now-unused wallet arg from
hintsRemaining. The FBS field is tombstoned `(deprecated)` (not deleted) so the vtable
slots after it stay stable across a rolling deploy; no accessor is generated. HintResult
keeps wallet_balance (the real post-spend payments balance the client adopts into the
profile). The StateView type no longer has walletBalance, so the clobber cannot return
without a compile error.

Tests: hintsRemaining (2-arg); hints.hintsLeft (allowance + live wallet, no strip); the
game state/hint integration (allowance-only HintsRemaining); gateway transcode; FBS regen.

ui/src/lib/model.ts

@@ -78,17 +78,14 @@ export interface MoveRecord {
   total: number;
 }
 
-/** A seated player's private view of a game. hintsRemaining folds the per-game allowance
- *  together with the global wallet; walletBalance is the wallet alone, so the client can
- *  derive the per-game allowance (hintsRemaining - walletBalance) and keep the wallet live
- *  across games (see lib/hints). */
+/** A seated player's private view of a game. hintsRemaining is the per-game allowance alone; the
+ *  purchasable hint wallet lives on the profile (payments), and the client adds it (see lib/hints). */
 export interface StateView {
   game: GameView;
   seat: number;
   rack: string[];
   bagLen: number;
   hintsRemaining: number;
-  walletBalance: number;
   /** For a vs_ai game, the seconds until the idle hint unlocks (computed by the source: the SERVER
    *  clock online, the device clock offline) — 0/undefined while open (the human's first move, or a
    *  non-vs_ai game). The client anchors a MONOTONIC countdown (performance.now()) to it on receipt,