feat(contribute): upload event images to OneDrive before submission

- ApiClient.uploadFile() — multipart POST to /v1/upload/file (60s timeout)
- ApiEndpoints.uploadFile — points to Node.js upload endpoint
- GamificationService.submitContribution() now uploads each picked image
  to OneDrive via the server upload pipeline, then passes the returned
  { fileId, url, ... } objects as `media` in the submission body
  (replaces broken behaviour of sending local device paths as strings)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/features/auth/services/auth_service.dart

@@ -60,6 +60,18 @@ class AuthService {
       // Save phone if provided (optional)
       if (res['phone_number'] != null) await prefs.setString('phone_number', res['phone_number'].toString());
 
+      // Save profile photo from login response
+      final rawPhoto = res['profile_photo']?.toString() ?? '';
+      if (rawPhoto.isNotEmpty) {
+        final photoUrl = rawPhoto.startsWith('http') ? rawPhoto : 'https://em.eventifyplus.com$rawPhoto';
+        await prefs.setString('profileImage_$savedEmail', photoUrl);
+        await prefs.setString('profileImage', photoUrl);
+      }
+
+      // Save Eventify ID
+      final eventifyId = res['eventify_id']?.toString() ?? '';
+      if (eventifyId.isNotEmpty) await prefs.setString('eventify_id', eventifyId);
+
       PostHogService.instance.identify(savedEmail, properties: {
         'username': displayCandidate,
         'login_method': 'email',
@@ -178,6 +190,18 @@ class AuthService {
       }
       if (res['phone_number'] != null) await prefs.setString('phone_number', res['phone_number'].toString());
 
+      // Save profile photo from Google login response
+      final rawPhoto = res['profile_photo']?.toString() ?? '';
+      if (rawPhoto.isNotEmpty) {
+        final photoUrl = rawPhoto.startsWith('http') ? rawPhoto : 'https://em.eventifyplus.com$rawPhoto';
+        await prefs.setString('profileImage_$serverEmail', photoUrl);
+        await prefs.setString('profileImage', photoUrl);
+      }
+
+      // Save Eventify ID
+      final eventifyId = res['eventify_id']?.toString() ?? '';
+      if (eventifyId.isNotEmpty) await prefs.setString('eventify_id', eventifyId);
+
       PostHogService.instance.identify(serverEmail, properties: {
         'username': displayName,
         'login_method': 'google',