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/game/Game.svelte

@@ -251,7 +251,8 @@
       view = st;
       // Anchor the vs_ai idle-hint countdown to the freshly fetched seconds-left (0 = open / non-vs_ai).
       armHintGate(st.game.vsAi ? (st.hintUnlockLeftSeconds ?? 0) : 0);
-      syncWallet(st.walletBalance);
+      // The game state no longer carries the hint wallet (it lives on the profile); do not touch
+      // app.profile.hintBalance here — that would clobber the authoritative payments balance.
       // Seed the unread flag from the authoritative state (the live stream only raises it).
       seedChatUnread(id, st.game.unreadChat, st.game.unreadMessages);
       moves = hist.moves;
@@ -833,10 +834,9 @@
       seat: r.move.player,
       rack: r.rack,
       bagLen: r.bagLen,
-      // A move is not a hint, so the per-game allowance and the wallet are unchanged: carry both
-      // forward (their difference is the stable allowance; the badge adds the live wallet).
+      // A move is not a hint, so the per-game allowance is unchanged: carry it forward. The badge
+      // adds the live wallet from the profile.
       hintsRemaining: view?.hintsRemaining ?? 0,
-      walletBalance: view?.walletBalance ?? 0,
     };
     // The move result is an authoritative per-viewer view: a nudge the actor just answered by
     // moving is already cleared server-side, so reconcile the unread flag from it.
@@ -1047,7 +1047,7 @@
           recenter++;
         }
         if (isCoarse() && !landscape) zoomed = true;
-        view = { ...view, hintsRemaining: h.hintsRemaining, walletBalance: h.walletBalance };
+        view = { ...view, hintsRemaining: h.hintsRemaining };
         syncWallet(h.walletBalance);
         // The hint is the engine's own top-ranked, fully scored legal move: reuse it as the
         // preview instead of a redundant evaluate (same engine call, same placement). Cancel any