feat: browser-native client — wire SPA to the SDK, delete the Go gateway

Phase 2 of issue 0001. uniweb becomes a pure frontend (web/ only), like
unibus_android: the SPA talks directly to the bus and the Go gateway is gone.

- busService.ts: the new data layer over the bus SDK, replacing the old api module.
  It holds the user's wallet identity and a connected BusClient IN THE BROWSER and
  opens the session locally — the private key is never sent anywhere (closes the
  gateway-era hole where the browser POSTed its private key to /api/session).
- Wire account/App/ChatShell/ChatPanel/WalletLogin/Recover/Join to busService;
  subscribeRoom replaces the SSE streamRoom; ApiError -> SessionError.
- SDK: ControlPlane.createRoom + listMemberRooms, and fetchRoom mapped to the real
  control-plane wire shape (snake_case, no id) — all verified by the live round-trip.
- Delete cmd/webgw, go.mod, go.sum, src/api.ts and the orphan operator Login. uniweb
  now has zero Go and no dependency on unibus as a module.
- vite: drop the /api proxy, dev server on 5173 to match the bus CORS allowlist; add
  vite-env typings. app.md: lang ts, no uses_functions, e2e_checks are now web-only.
  Bump 0.3.0.

Onboarding by token is now admin-side (the bus has no self-register endpoint; the
gateway only mocked it). tsc + pnpm build + 19/19 unit green.

web/vite.config.ts

@@ -3,12 +3,12 @@ import react from "@vitejs/plugin-react";
 
 export default defineConfig({
   plugins: [react()],
-  // En dev, /api (REST + SSE) se proxea al gateway Go (cmd/webgw, puerto 8481).
-  // El proxy hace streaming, así que el SSE de /api/rooms/{id}/stream funciona a
-  // través de él. En producción el gateway sirve el dist embebido y no hay proxy.
+  // The SPA talks DIRECTLY to the bus (signed HTTPS control plane + nats.ws data
+  // plane), so there is no gateway and no /api proxy. The dev server runs on 5173 to
+  // match the bus CORS allowlist (--cors-origins http://localhost:5173). Point the
+  // SPA at a cluster node with VITE_BUS_HTTP / VITE_BUS_WS (see busService.ts).
   server: {
     host: true,
-    port: 5183,
-    proxy: { "/api": "http://127.0.0.1:8481" },
+    port: 5173,
   },
 });