Make filenames shorter

[hugobuddel]

As discussed on slack...

The filenames end up in FITS headers in cards like

HIERARCH ESO PRO REC1 CAL2 NAME= 'MASTER_IMG_FLT_LMP_LM_20251128T142225111.fits'

The stem of the filename should therefore be at most 40 characters.

It might be a better idea to just hack pyesorex / pycpl to allow HIERARCH + CONTINUE keywords in the FITS files.

[sesquideus]

I am still slightly worried about something even longer appearing somewhere, but I do not have any better ideas. And definitely a simpler workaround than modifying CPL.

[hugobuddel]

Let's not yet merge this and come back to discussing this later.

The filenames at the start of the workflow (detlin and dark) are short enough to test the archive infrastructure.

(Well, they are still to large, but just matching files based on the start of the names is working well enough for now.)

I'd like to give patching the ESO stack to allow HIERARCH+CONTINUE a try. We should still keep something like this P.R. in our back pocket in case we cannot get ESO to budge.

Some pipelines add their own provenance headers called just PROV1, PROV2 etc, so they have more space for the filename. Also, just the CONTINUE keyword (not in combination with HIERARCH) is now part of the FITS spec, so the ESO stack should support reading those in order to claim they are standard compliant.