Stage 7 (wip): UI shell, libs, mock transport, screens (lobby->game), e2e smoke

- plain Svelte 5 + TS + Vite (no SvelteKit); CSS-token design system (Telegram-ready), hash router, IndexedDB session
- pure libs: domain model, premium/value maps ported from solver, board replay, placement state machine, i18n en/ru
- in-memory mock transport + seed data; pnpm start runs lobby->active game->board with no backend
- board: pointer-drag + tap placement, MakeMove (popup / 1s-hold commit), two-state zoom, blank chooser, exchange, hint, word-check, chat
- Playwright smoke (mock) green; svelte-check clean; mock bundle ~37 KB gzip

ui/src/lib/gateway.ts

@@ -0,0 +1,13 @@
+// The single GatewayClient the app uses. In `mock` mode (pnpm start) it is the
+// in-memory fake; otherwise it is the real Connect/FlatBuffers transport. MODE is a
+// build-time constant, so a production build tree-shakes the mock away.
+
+import type { GatewayClient } from './client';
+import { MockGateway } from './mock/client';
+import { createTransport } from './transport';
+
+const isMock = import.meta.env.MODE === 'mock';
+
+export const gateway: GatewayClient = isMock
+  ? new MockGateway()
+  : createTransport(import.meta.env.VITE_GATEWAY_URL ?? '');