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/i18n/locales/en/conversation.json

@@ -27,6 +27,8 @@
   "recentChats": "Recent Chats",
   "stopReadingAloud": "Stop reading aloud",
   "readAloudAgain": "Play again",
+  "readAloudPause": "Pause reading",
+  "readAloudResume": "Resume reading",
   "cannotReadAloud": "Read unavailable",
   "readingAloud": "Reading aloud…",
   "recordingPermissionDenied": "Microphone permission is required to record",

app-expo/src/i18n/locales/en/profile.json

@@ -33,6 +33,29 @@
     "title": "Data & Privacy"
   },
   "editAvatar": "Edit Profile Picture",
+  "personalInfo": {
+    "avatarPresetFailed": "Could not set preset avatar",
+    "avatarUploadFailed": "Could not upload avatar",
+    "cancel": "Cancel",
+    "birthPlacePlaceholder": "Birthplace",
+    "birthYearPlaceholder": "Birth year",
+    "changeAvatar": "Change photo",
+    "chooseFromLibrary": "Choose from library",
+    "choosePreset": "Preset avatars",
+    "grewUpPlaceholder": "Where you grew up",
+    "libraryPermissionDenied": "Photo library access is required to pick an image",
+    "nickname": "Nickname",
+    "nicknamePlaceholder": "Enter nickname",
+    "nicknameRequired": "Please enter a nickname",
+    "occupationPlaceholder": "Occupation",
+    "presetPickTitle": "Choose a preset",
+    "save": "Save",
+    "saveFailed": "Could not save",
+    "savePartialBody": "Your nickname was saved, but profile fields below could not be saved. Check your connection and tap Save again.",
+    "savePartialTitle": "Partially saved",
+    "saving": "Saving…",
+    "title": "Personal info"
+  },
   "helpSupport": {
     "faq": "FAQ",
     "feedback": "Feedback & Support",