KiVar testing

Nobody has claimed this yet.

I have prepared a little testing pcb file for KiVar: [errors.zip](https://github.com/markh-de/KiVar/files/14509200/errors.zip). This one should test, if KiVar discovers and correctly reports an error. Righ now, I manually open the KiVar gui and read through all the errors. In the future, this could be done by `kivar-cli` and script which will parse and check the output.

My next idea is to prepare similar board with more tests - changing values of components, changing DNP, case sensitivity for aspects and choices naming ... In this case, KiVar should not report and error, instead it shoul run and perform variant switching. After that, Pick-and-Place file would be generated and compared to the correct one, which was manually checked. This could be also automated by `kivar-cli` and some scripts.

More ideas and feedback are welcomed, especially:
- it this even right way, how to test KiVar?
- what else should be tested? Where could be bugs?
- way of collaboration on this - Should I fork KiVar repository and create pull request or create another repo? Sending pcb file zipped as attachment to issue is not comfortable ...

Start by reviewing the attached errors.zip and the current kivar-cli output. Define the scope for automated error detection, variant switching, and Pick-and-Place comparison, then identify where these checks belong. Done should include a documented, repeatable test workflow that distinguishes expected errors from successful variant generation.

Written by the indexing model from the issue text.