[thdxr]

on apple laptop keyboards the microphone (dictation) key in the top row is a normal keyDown/keyUp for virtual keycode 176 with SecondaryFn always set (observed flags 0x800100). the recorder had no character for it, so it said "unsupported key", and a binding that implied Fn would never match anyway.

this adds a macOS-only Labs feature, off by default, under Shortcuts: Microphone key alone (microphone-key, labs.microphone_key). with it on, the recorder takes the key by itself and saves {code: 176, label: "Mic"}, and hex settings set dictation_hotkey mic|microphone works too. matching ignores SecondaryFn for this one key only, so Fn stays significant for every other key.

the lab gates every shortcut on that key, with or without modifiers. with the lab off nothing changes from before this feature: the window refuses the key as "Unsupported key", hex settings refuses it pointing at hex labs on microphone-key, and any saved shortcut on the microphone key is put back to its default when settings load or the toggle turns off.

if macOS's own Dictation still opens, the key may be handled before Hex's event tap sees it; the card and docs say to move macOS's dictation shortcut in System Settings › Keyboard › Dictation.

closes #181

thanks @ViaxCo for the detailed investigation of the key code and Fn flag in the issue.