feat(payments): wallet screen with balances, benefits and storefront

Add the "Кошелёк" section to the settings hub: context-visible chip
balances, active benefits (no-ads term/forever, hints) and a storefront of
chip-priced values and money-priced chip packs. Guests have no wallet; the
Google Play build hides the money purchases behind a RuStore stub; a web
purchase that would draw VK/Telegram chips warns first.

Add the catalog read path the storefront needs — a context-projected
GET /api/v1/user/wallet/catalog (payments service + store, gateway op
wallet.catalog, FBS Catalog/CatalogProduct/CatalogAtom, client decode) —
plus the client leg for the existing wallet.get/buy ops. Value spends reuse
the existing spend path; the chip-pack purchase (money order flow) arrives
with payment intake, so its action is a disabled placeholder for now.

Covered by Go unit (catalog projection) + integration (/wallet/catalog over
Postgres), vitest (formatting, spendable selection, web-spend warning, GP
flag, codec + gateway encode round-trips) and Playwright mock e2e (render,
guest-hidden, GP stub, warning) on Chromium + WebKit.

ui/src/lib/i18n/en.ts

@@ -225,6 +225,33 @@ export const en = {
   'offline.promptYes': 'Enable',
   'offline.promptNo': 'Keep trying',
 
+  // --- wallet ---
+  'wallet.title': 'Wallet',
+  'wallet.tab': 'Wallet',
+  'wallet.balance': 'Balance',
+  'wallet.noChips': 'No chips yet',
+  'wallet.source.vk': 'VK',
+  'wallet.source.telegram': 'Telegram',
+  'wallet.source.direct': 'Web',
+  'wallet.viewOnly': 'view only',
+  'wallet.benefits': 'Benefits',
+  'wallet.noAdsUntil': 'No ads until {date}',
+  'wallet.noAdsForever': 'No ads forever',
+  'wallet.adsOn': 'Ads are on',
+  'wallet.hints': 'Hints {n}',
+  'wallet.store': 'Store',
+  'wallet.empty': 'The store is empty for now',
+  'wallet.buy': 'Buy',
+  'wallet.soon': 'Soon',
+  'wallet.gpStub': 'To buy chips, install the RuStore build.',
+  'wallet.cur.RUB': '₽',
+  'wallet.cur.VOTE': 'votes',
+  'wallet.cur.XTR': '⭐',
+  'wallet.warnTitle': 'Web-only purchase',
+  'wallet.warnBody':
+    'This spends your VK/Telegram chips, and the benefit will work on the web and in the app only — because of store rules.',
+  'wallet.warnConfirm': 'Continue',
+  'wallet.warnCancel': 'Cancel',
   'about.title': 'About',
   'about.tab': 'Info',
   'about.description': 'A multiplatform Scrabble game.',