feat(mobile): imagePicker helper with library + camera flows

apps/mobile/lib/imagePicker.ts

@@ -0,0 +1,48 @@
+import * as ImagePicker from 'expo-image-picker';
+
+export interface PickedImage {
+  uri: string;
+  mimeType: string;
+  sizeBytes: number;
+  width: number;
+  height: number;
+}
+
+// Pick an image from the photo library. Requests permission on demand;
+// returns null on cancel / denial.
+export async function pickFromLibrary(): Promise<PickedImage | null> {
+  const perm = await ImagePicker.requestMediaLibraryPermissionsAsync();
+  if (!perm.granted) return null;
+  const res = await ImagePicker.launchImageLibraryAsync({
+    mediaTypes: ImagePicker.MediaTypeOptions.Images,
+    quality: 0.85,
+    base64: false,
+    exif: false,
+  });
+  if (res.canceled || res.assets.length === 0) return null;
+  return toPicked(res.assets[0]!);
+}
+
+// Capture an image via the device camera. Same return shape as
+// pickFromLibrary so call sites can stay shape-agnostic.
+export async function captureFromCamera(): Promise<PickedImage | null> {
+  const perm = await ImagePicker.requestCameraPermissionsAsync();
+  if (!perm.granted) return null;
+  const res = await ImagePicker.launchCameraAsync({
+    quality: 0.85,
+    base64: false,
+    exif: false,
+  });
+  if (res.canceled || res.assets.length === 0) return null;
+  return toPicked(res.assets[0]!);
+}
+
+function toPicked(asset: ImagePicker.ImagePickerAsset): PickedImage {
+  return {
+    uri: asset.uri,
+    mimeType: asset.mimeType ?? 'image/jpeg',
+    sizeBytes: asset.fileSize ?? 0,
+    width: asset.width,
+    height: asset.height,
+  };
+}