[IDEA] Creating a cfg-file for a department
The aim is to have one `.cfg`-file for each department. In this department all things are defined that are e.g. not person specific.
The `.cfg`-file should be applicable to letter, beamer and poster.
Here is an approach. However as far as I see in the `rwth-letter.sty` there is no `\c__ptxcd_base_str` filled. (cf. https://gitlab.git.nrw/rwth-it-center/rwth-latex-templates/rwth-ci/-/blame/main/tex/rwth-ci.dtx?ref_type=heads#L209)
```
\ProvidesFile{rwth-itcenter.cfg}[2026-11-15 Common information about IT Center]
\ExplSyntaxOn
\str_if_in:NnT \c__ptxcd_base_str {letter}
{
%------------------ letter
\setkomavar{frominstitution-short}{MYINSTITUT}
\setkomavar{frominstitution-id}{010420}
\setkomavar{fromaddress}{Musterstraße 7\\52074 Aachen\\GERMANY}
\setkomavar{fromurl}{https://mi.rwth-aachen.de/}
\setkomavar{fromvat}{DE\,121\,689\,807}
\setkomavar{fromtax}{201/5930/5005}
\setkomavar*{frombank}{RWTH Aachen University}
\setkomavar{frombank}{
Kontoinhaber\\
Name der Bank\\
Konto 000\,000\,000\\% optional
BLZ 000\,000\,00\\% optional
SWIFT-BIC: ABCDEF1\\
IBAN: DE00\,0000\,0000\,0000\,0000\,00
}
%--------------- letter end
}
\str_if_in:NnT \c__ptxcd_base_str {beamer}
{
%------------------ beamer
%....
}
\ExplSyntaxOff
```
issue