Dev
ac74d31933
feat(04-03): implement FileTransferService with MoveCopyUtil and conflict policies
- FileTransferService.cs: CSOM copy/move via MoveCopyUtil.CopyFileByPath/MoveFileByPath
- Conflict policies: Skip (catch ServerException), Overwrite (overwrite=true), Rename (KeepBoth=true)
- ResourcePath.FromDecodedUrl for special character support
- Recursive folder enumeration with system folder filtering
- EnsureFolderAsync creates intermediate destination folders
- Best-effort metadata preservation (ResetAuthorAndCreatedOnCopy=false)
- FileTransferServiceTests.cs: 4 passing tests, 3 skipped (integration)