feat(profile): avatar presets, upload, nickname editing

- FastAPI: preset assets 01–08, GET list/static, PUT /me/avatar/preset,
  safer uploaded-avatar path validation, preset_avatars + HTTP tests.
- Expo: personal-info (library + presets), profile tab avatar,
  resolveApiMediaUrl, auth hooks cache sync, Web multipart helper,
  partial-save messaging + profile i18n.
- Includes existing edits to conversation screen and voice use-player.

Co-authored-by: Cursor <cursoragent@cursor.com>

app-expo/tests/features/voice/use-player.test.tsx

@@ -1,5 +1,6 @@
-import { renderHook } from '@testing-library/react-native';
+import { act, renderHook } from '@testing-library/react-native';
 
+import { audioFocus } from '@/core/audio/audio-focus';
 import { usePlayer } from '@/features/voice/hooks/use-player';
 
 const mockUseAudioPlayer = jest.fn();
@@ -34,6 +35,8 @@ describe('usePlayer', () => {
       currentTime: 0,
       duration: 0,
     });
+    jest.mocked(audioFocus.acquireForPlayback).mockResolvedValue(true);
+    jest.mocked(audioFocus.releaseIfOwnedBy).mockResolvedValue(undefined);
   });
 
   test('keeps the native audio session active while app-level audio focus owns teardown', () => {
@@ -47,4 +50,81 @@ describe('usePlayer', () => {
       }),
     );
   });
+
+  test('pausePlayback toggles playing→paused and invokes native pause', async () => {
+    mockUseAudioPlayerStatus.mockReturnValue({
+      isLoaded: true,
+      playing: true,
+      currentTime: 0.1,
+      duration: 10,
+    });
+    const pause = jest.fn();
+    const play = jest.fn();
+    mockUseAudioPlayer.mockReturnValue({ pause, play });
+
+    const { result } = renderHook(() => usePlayer());
+
+    await act(async () => {
+      await result.current.enqueueExclusive({
+        uri: 'file:///fixture.mp3',
+        kind: 'voice',
+      });
+    });
+
+    expect(result.current.status).toBe('playing');
+
+    act(() => {
+      result.current.pausePlayback();
+    });
+
+    expect(pause).toHaveBeenCalled();
+    expect(result.current.status).toBe('paused');
+  });
+
+  test('resumePlayback toggles paused→playing and invokes native play', async () => {
+    mockUseAudioPlayerStatus.mockReturnValue({
+      isLoaded: true,
+      playing: false,
+      currentTime: 0.1,
+      duration: 10,
+    });
+    const pause = jest.fn();
+    const play = jest.fn();
+    mockUseAudioPlayer.mockReturnValue({ pause, play });
+
+    const { result } = renderHook(() => usePlayer());
+
+    await act(async () => {
+      await result.current.enqueueExclusive({
+        uri: 'file:///fixture.mp3',
+        kind: 'voice',
+      });
+    });
+
+    act(() => {
+      result.current.pausePlayback();
+    });
+    expect(result.current.status).toBe('paused');
+
+    await act(async () => {
+      await result.current.resumePlayback();
+    });
+
+    expect(play).toHaveBeenCalled();
+    expect(result.current.status).toBe('playing');
+  });
+
+  test('pausePlayback is a no-op while idle', async () => {
+    const pause = jest.fn();
+    mockUseAudioPlayer.mockReturnValue({ pause, play: jest.fn() });
+
+    const { result } = renderHook(() => usePlayer());
+
+    act(() => {
+      result.current.pausePlayback();
+    });
+
+    expect(pause).not.toHaveBeenCalled();
+    expect(result.current.status).toBe('idle');
+  });
 });