P1: prepareDirectUpload and completeDirectUpload now require project_id,
uploadAssetDirect calls getOrCreateDefaultProject() to obtain it automatically.
P2: MAX_FILE_SIZE changed from 2*1024^3 to 2048*1024*1024 to align with
backend OSS_DIRECT_UPLOAD_MAX_MB=2000.
- Add MAX_FILE_SIZE (2GB) validation in handleUpload with friendly error message
- Route files >100MB through OSS presigned direct upload (uploadAssetDirect)
- Keep small file form upload (uploadAsset) for files <=100MB
- Update upload hint text to show '单文件不超过 2GB' limit
- Add directUploadMutation with proper loading state tracking
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>