Add buff75 VIA

[Vem-596]

Description

Add buff75 VIA

QMK Pull Request

qmk/qmk_firmware#24297

Checklist

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

[Cipulot]

@Vem-596 PR in waiting status since the QMK main merge is not been performed, as well as the VIA Keymap.