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>

api/app/features/auth/schemas.py

@@ -104,3 +104,18 @@ class UpdateNicknameRequest(BaseModel):
 
 class AvatarUploadResponse(BaseModel):
     avatar_url: str
+
+
+class SetAvatarPresetRequest(BaseModel):
+    preset_id: str = Field(
+        ...,
+        min_length=2,
+        max_length=2,
+        pattern=r"^\d{2}$",
+        description="预设编号，如 01–08",
+    )
+
+
+class AvatarPresetItem(BaseModel):
+    id: str
+    url: str