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/src/core/api/media-url.ts

@@ -0,0 +1,14 @@
+import { config } from '@/core/config';
+
+/** 将 API 返回的相对路径（如 `/api/auth/avatars/x.jpg`）转为可请求的绝对 URL。 */
+export function resolveApiMediaUrl(
+  pathOrUrl: string | null | undefined,
+): string | null {
+  if (pathOrUrl == null || pathOrUrl === '') return null;
+  if (/^https?:\/\//i.test(pathOrUrl)) return pathOrUrl;
+  if (pathOrUrl.startsWith('/')) {
+    const base = config.apiBaseUrl.replace(/\/$/, '');
+    return `${base}${pathOrUrl}`;
+  }
+  return pathOrUrl;
+}