KiCad 6 migration

[scottbez1]

KiCad 6 is out! All electronics projects should be updated and verified under KiCad 6.

A few areas of concern that come to mind:

• KiKit (currently using a custom fork to add V-Cut support https://github.com/scottbez1/KiKit/tree/vcutlayer which should be possible with the new CLI options in KiKit v1)
• KiBot - need to make sure everything works as expected under 6
• Checking, updating, or deprecating other KiCad automation scripts, like PCB SVG export and 3d rendering (maybe possible to switch to KiBot for these now?)