Adds Intel support.
The DDC code path (IOAVServiceWriteI2C) only exists on Apple Silicon, so on Intel Macs it now compiles out and every external display falls through to software gamma dimming (CGSetDisplayTransferByFormula). Apple-native externals (Studio Display, Pro Display XDR) continue to use DisplayServicesSetBrightness on both architectures.
No behavior change on Apple Silicon.
Install
brew install emin93/tap/ddc-mirror
brew services start ddc-mirror