Add new VULCAN instrument geometry

[peterfpeterson]

This is the new IDF for VULCAN in spring 2026. Luc created it and I have tested it.

There is no associate issue, but this is associated with EWM15052

To test:

LoadEventNexus with VULCAN_260112.nxs.h5, then reload the file (to a different workspace) with LoadNexusInstrumentXML=False to get the IDF from this file.

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[lldj15]

Looks fine