chore(mobile): drop deprecated deviceAssetId / deviceId from upload fields (#28384)

server removed both fields from AssetMediaCreateDto in #27818. zod silently strips unknown fields so uploads still work, but we send dead weight on every request.

drop from foreground + background upload paths + share intent path. deviceAssetId stays as the internal background_downloader taskId, just not in the multipart form fields anymore.

mobile/lib/services/background_upload.service.dart

@@ -394,12 +394,9 @@ class BackgroundUploadService {
     final serverEndpoint = Store.get(StoreKey.serverEndpoint);
     final url = Uri.parse('$serverEndpoint/assets').toString();
     final headers = ApiService.getRequestHeaders();
-    final deviceId = Store.get(StoreKey.deviceId);
     final (baseDirectory, directory, filename) = await Task.split(filePath: file.path);
     final fieldsMap = {
       'filename': originalFileName ?? filename,
-      'deviceAssetId': deviceAssetId ?? '',
-      'deviceId': deviceId,
       'fileCreatedAt': createdAt.toUtc().toIso8601String(),
       'fileModifiedAt': modifiedAt.toUtc().toIso8601String(),
       'isFavorite': isFavorite?.toString() ?? 'false',