feat(android): resolve gateway origin on native, skip SW, hide MVP purchases

Make the web SPA behave correctly inside the Capacitor native shell, where the
bundle loads from a local origin:

- New lib/origin.ts gatewayOrigin(): absolute URLs resolve to VITE_GATEWAY_URL on
  native (the finished-game export/share URL in Game.svelte and the Wallet
  site-root link), falling back to the page origin on web. transport.ts already
  resolved via VITE_GATEWAY_URL and is left as-is.
- Skip the PWA service worker on the native channel (the assets are already local;
  a worker would risk serving stale content across store updates).
- Hide the money-purchase UI in the MVP: new distribution.purchasesHidden() folds
  VITE_PAYMENTS_DISABLED and the Google Play flag. The Wallet "buy" tab shows a
  neutral, pointer-free note (wallet.purchasesSoon) for the RuStore MVP and keeps
  the RuStore stub Google-Play-only. A ?nopay mock force mirrors ?gp for the e2e.
- Native env types in vite-env.d.ts.

Client-only, contour-safe: no wire/proto/schema change; web/VK/Telegram unchanged.
Tests: origin + purchasesHidden unit tests, a ?nopay wallet e2e. svelte-check
clean, vitest green, web + native vite build clean.

ui/src/lib/i18n/en.ts

@@ -252,6 +252,7 @@ export const en = {
   'wallet.iosBlockedLink': 'other version',
   'wallet.iosBlockedPost': ' of the game.',
   'wallet.gpStub': 'To buy chips, install the RuStore build.',
+  'wallet.purchasesSoon': 'Purchases will be available in a future update.',
   'wallet.cur.RUB': '₽',
   'wallet.cur.VOTE': 'votes',
   'wallet.cur.XTR': '⭐',

ui/src/lib/i18n/ru.ts

@@ -252,6 +252,7 @@ export const ru: Record<MessageKey, string> = {
   'wallet.iosBlockedLink': 'другой версией',
   'wallet.iosBlockedPost': ' игры.',
   'wallet.gpStub': 'Чтобы покупать фишки, установите версию из RuStore.',
+  'wallet.purchasesSoon': 'Покупки появятся в одном из следующих обновлений.',
   'wallet.cur.RUB': '₽',
   'wallet.cur.VOTE': 'голосов',
   'wallet.cur.XTR': '⭐',