Add support for Geistmaschine Geist

[ebastler]

Add support for Geistmaschine Geist (v3 only, board will not be sold with older firmware)

Description

QMK Pull Request

qmk/qmk_firmware#20117

Checklist

• The VIA support for this keyboard is MERGED in QMK master already (MANDATORY)
• The VIA definition follows the guide here: https://caniusevia.com/docs/layouts
• I have a V3 JSON version for this keyboard definition.(MANDATORY)
• I have tested this keyboard definition using VIA's "Design" tab.
• I have tested this keyboard definition with firmware on a device.
• I have assigned alpha keys and modifier keys with the correct colors.
• The Vendor ID is not 0xFEED