Feature request: use Apple Keyboard's dictation button

**Is your feature request related to a problem? Please describe.**
Hex is so much better than Apple's build in Dictation feature. It's also hard finding a keyboard shortcut that doesn't interfere with other applications.

**Describe the solution you'd like**
Not sure if it's even possible, but it would be awesome if I could just hold down the `[🎙️]` dictation key to use Hex instead of Apple's version.

**Describe alternatives you've considered**
I tried disabling Apple dictation and setting this as a shortcut but it didn't work.

No file or test is named. Start by verifying whether macOS exposes the Apple Keyboard dictation key to apps and how the legacy Swift app currently handles shortcuts; done means holding that key invokes Hex without Apple's dictation.

Written by the indexing model from the issue text.