fix(mobile): handle file picker cancellation

mobile-uni/src/services/case.ts

@@ -8,6 +8,7 @@ import type {
   CaseUploadResponse
 } from '@/types/api';
 import { apiRequest, apiUrl, authHeaders, authenticatedFileUrl, readTextPayload } from './api';
+import { fileSelectionFailure } from '../utils/file-selection';
 
 const audioExtensions = ['.mp3', '.wav', '.m4a', '.webm', '.aac', '.ogg'];
 
@@ -31,7 +32,7 @@ export const chooseCaseAudio = () =>
           size: Number(file.size || 0)
         });
       },
-      fail: () => reject(new Error('未选择音频'))
+      fail: (error) => reject(fileSelectionFailure(error, '音频'))
     });
   });