6b95600260
In VDS mode the per-image ROI results (max/sum/sum_sq/npixel/x/y) are written into the data files but were not exposed in the master, so a VDS master surfaced no ROI statistics. Add virtual datasets under /entry/roi/<name> in LinkToData_VDS, one group per ROI, mirroring how the spot-finding and azimuthal-integration arrays are linked. Integrated and legacy formats are unaffected (the results are already reachable there). Extended the reader round-trip test to write real ROI results and check they read back from the master for both VDS and integrated formats. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>