Fix profile picture uploads from the app

Expo's fetch rejects React Native's { uri, name, type } FormData parts ("Unsupported FormDataPart
implementation"), so every upload failed. Upload an expo-file-system File instead, shrunk to 1024 px
first. The server also takes bigger photos (25 MB, sharp's default pixel limit) and logs why a
picture couldn't be read.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011Y2iUsKEWDuRGjK5FPmcUP

apps/mobile/package.json

@@ -12,10 +12,12 @@
     "expo-camera": "~57.0.6",
     "expo-constants": "~57.0.20",
     "expo-device": "~57.0.2",
+    "expo-file-system": "~57.0.7",
     "expo-font": "~57.0.4",
     "expo-glass-effect": "~57.0.4",
     "expo-haptics": "~57.0.3",
     "expo-image": "~57.0.5",
+    "expo-image-manipulator": "~57.0.21",
     "expo-image-picker": "~57.0.20",
     "expo-linear-gradient": "~57.0.2",
     "expo-linking": "~57.0.11",