fix(android): use system photo picker

Block broad image and video read permissions in Expo config and the checked-in Android manifest. Keep picker access scoped to user-selected media and gallery saves write-only. Add regression coverage and document the release-manifest invariant.

apps/mobile/src/hooks/useAvatarPicker.ts

@@ -100,13 +100,17 @@ export function useAvatarPicker(options?: UseAvatarPickerOptions): UseAvatarPick
                     quality: 0.8,
                     exif: false,
                 });
-            } else {
-                const { status } = await ImagePicker.requestMediaLibraryPermissionsAsync();
-                if (status !== 'granted') {
-                    Alert.alert('Permission Denied', 'Photo library access is required to choose a photo.');
-                    return;
-                }
-                result = await ImagePicker.launchImageLibraryAsync({
+            } else {
+                // Android's system photo picker grants the selected file directly, so
+                // selecting an avatar does not need broad media-library access.
+                if (Platform.OS !== 'android') {
+                    const { status } = await ImagePicker.requestMediaLibraryPermissionsAsync();
+                    if (status !== 'granted') {
+                        Alert.alert('Permission Denied', 'Photo library access is required to choose a photo.');
+                        return;
+                    }
+                }
+                result = await ImagePicker.launchImageLibraryAsync({
                     mediaTypes: ['images'],
                     allowsEditing: true,
                     aspect: [1, 1],