feat(mobile): keep voice alive with the screen off

A call dropped as soon as the screen locked. The cause is not configuration:
Android freezes background processes, and a frozen WebView stops running the
JavaScript that holds the LiveKit connection up. The only thing the system
accepts as "this app must keep running" is a foreground service, which is why
the persistent notification comes with it.

Two mechanisms, both needed: the service stops the process from being frozen,
and a partial wake lock stops the CPU from sleeping. Either one alone still
drops the call.

The notification carries a hangup action. The service cannot end the call
itself — only the web app knows how to leave a LiveKit room — so it notifies
the plugin's listeners and the web side disconnects through the same path the
in-app button uses.

The web side starts the service on mount when a call is already in progress,
not just on transition: the WebView can reload mid-call, and waiting for the
next connect would leave that call unprotected with no visible symptom until
someone locked their screen.

POST_NOTIFICATIONS is requested at launch on Android 13+. Denying it does not
drop calls — the service still runs — it only hides the notification.

Tests cover connect/disconnect, the already-in-a-call mount, the hangup action,
and that the component is inert in the browser and desktop builds. Verified by
mutation that dropping the start call fails the first one.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/web/src/components/voice/AndroidVoiceService.test.tsx

@@ -0,0 +1,110 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+import { render, act, waitFor } from '@testing-library/react';
+
+// A voiceStore arrasta o AudioManager, que carrega um AudioWorklet inexistente
+// no jsdom. Mesmo stub que os outros testes que tocam nesta store usam.
+vi.mock('../../audio/AudioManager', () => ({
+  AudioManager: { getInstance: () => ({ resumeContext: vi.fn() }) },
+}));
+
+import { AndroidVoiceService } from './AndroidVoiceService';
+import { useVoiceStore } from '../../stores/voiceStore';
+
+const start = vi.fn(() => Promise.resolve());
+const stop = vi.fn(() => Promise.resolve());
+let hangupHandler: (() => void) | null = null;
+
+function installCapacitor(platform = 'android') {
+  (globalThis as { Capacitor?: unknown }).Capacitor = {
+    isNativePlatform: () => true,
+    getPlatform: () => platform,
+    Plugins: {
+      VoiceForeground: {
+        start,
+        stop,
+        addListener: (_e: string, h: () => void) => {
+          hangupHandler = h;
+          return Promise.resolve({ remove: () => { hangupHandler = null; } });
+        },
+      },
+    },
+  };
+}
+
+describe('AndroidVoiceService', () => {
+  beforeEach(() => {
+    start.mockClear();
+    stop.mockClear();
+    hangupHandler = null;
+    useVoiceStore.setState({ isLiveKitConnected: false, currentVoiceChannelId: null });
+  });
+
+  afterEach(() => {
+    delete (globalThis as { Capacitor?: unknown }).Capacitor;
+  });
+
+  it('starts the service when a call connects and stops it when it ends', async () => {
+    installCapacitor();
+    render(<AndroidVoiceService />);
+    expect(start).not.toHaveBeenCalled();
+
+    act(() => {
+      useVoiceStore.setState({ isLiveKitConnected: true, currentVoiceChannelId: 'c-1' });
+    });
+    await waitFor(() => expect(start).toHaveBeenCalledTimes(1));
+
+    act(() => {
+      useVoiceStore.setState({ isLiveKitConnected: false, currentVoiceChannelId: null });
+    });
+    await waitFor(() => expect(stop).toHaveBeenCalledTimes(1));
+  });
+
+  it('starts on mount when a call is already in progress', async () => {
+    // A WebView pode recarregar no meio da chamada. Se o servico so subisse na
+    // proxima transicao, a call seguiria desprotegida ate alguem sair e entrar
+    // de novo — e cairia ao trancar a tela.
+    installCapacitor();
+    useVoiceStore.setState({ isLiveKitConnected: true, currentVoiceChannelId: 'c-1' });
+
+    render(<AndroidVoiceService />);
+
+    await waitFor(() => expect(start).toHaveBeenCalledTimes(1));
+  });
+
+  it('leaves the call when the notification hangup is tapped', async () => {
+    installCapacitor();
+    const disconnectFn = vi.fn(() => Promise.resolve());
+    useVoiceStore.setState({ disconnectFn });
+
+    render(<AndroidVoiceService />);
+    await waitFor(() => expect(hangupHandler).not.toBeNull());
+
+    act(() => hangupHandler!());
+
+    expect(disconnectFn).toHaveBeenCalled();
+  });
+
+  it('does nothing outside the Android app', async () => {
+    // Mesmo componente montado no navegador e no desktop: nao pode tocar em
+    // nada nativo nem quebrar.
+    render(<AndroidVoiceService />);
+
+    act(() => {
+      useVoiceStore.setState({ isLiveKitConnected: true, currentVoiceChannelId: 'c-1' });
+    });
+
+    expect(start).not.toHaveBeenCalled();
+    expect(stop).not.toHaveBeenCalled();
+  });
+
+  it('ignores a web build of Capacitor', async () => {
+    installCapacitor('web');
+    render(<AndroidVoiceService />);
+
+    act(() => {
+      useVoiceStore.setState({ isLiveKitConnected: true, currentVoiceChannelId: 'c-1' });
+    });
+
+    expect(start).not.toHaveBeenCalled();
+  });
+});