VSI: make it easier to get calibration data

[melissalinkert]

See https://forum.image.sc/t/cellsens-deconvolved-images-vsi-float-loaded-with-inconsistent-intensity-scaling-via-bio-formats/118330/4 and data in https://zenodo.org/records/18163893.

At minimum, it would be good to have a more descriptive original metadata key to locate the calibration information. Likely the reader just doesn't recognize the appropriate tag number.

[imagesc-bot]

This issue has been mentioned on Image.sc Forum. There might be relevant details there:

https://forum.image.sc/t/cellsens-deconvolved-images-vsi-float-loaded-with-inconsistent-intensity-scaling-via-bio-formats/118330/6