Request PID EC00 for MCmacro by QuadState

[QuadState]

This pull request registers a new USB PID (EC00) for MCmacro,
a low-profile USB macro pad using Kailh Choc V2 mechanical switches.

ℹ️ Note: A separate PID request is open for ECmacro, which uses electrostatic-capacitive (Topre/NIZ style) switches.
MCmacro is identical in form factor but fitted with mechanical Kailh Choc V2 switches.

Device summary

• Open-source licenses
  • Firmware & code — MIT
  • Hardware docs — CC-BY-4.0
• Repository : https://github.com/QuadState/MCmacro

[tannewt]

Depends on #1043

[QuadState]

I appreciate you bringing this to our attention.

• KiCad project files added: MCmacro04 KiCad archive (ZIP)
  • Note: KiCad DRC will report clearance errors, but the actual copper-to-copper spacing exceeds 0.15 mm and meets JLCPCB’s (and other PCB fabs’) manufacturing requirements.
    This is because I intentionally enlarged the thermal relief gaps around the switch pads to improve soldering reliability.
• PCB updated to the latest revision
• Arduino firmware source remains unchanged in firmware/mcmacro04