Add system key events (media, volume, brightness) to hs.eventtap

[cmsj]

Fixes #268.

v2 had no equivalent of v1's hs.eventtap.event.newSystemKeyEvent(), so there was no way to post media keys. Only real media key events go through macOS's Now Playing routing, so hs.audiodevice or AppleScript workarounds don't cover play/next/previous (e.g. audio in a browser tab).

What's new

• hs.eventtap.makeSystemKeyEvent(key, isDown) returns an ordinary HSEventTapEvent, so .post()/.duplicate() work unchanged
• hs.eventtap.systemKeyStroke(key) presses and releases a key (5 ms between, like keyStroke)
• hs.eventtap.systemKeys lists the 22 v1 key names (PLAY, NEXT, SOUND_UP, BRIGHTNESS_UP, …) and their NX_KEYTYPE_* codes. Names are matched case-insensitively.
• hs.eventtap.eventTypes.systemDefined and event.systemKey ({key, keyCode, isDown, isRepeat}, or undefined for other events) let watchers recognise these keys

v1's down/repeat fields became isDown/isRepeat to match v2 style; the migration guide covers this. The docs warn about POWER/EJECT, and that synthetic brightness keys don't work on some Macs or external displays.

Testing

• 130 HSEventTapTests pass in a VM. The new tests check every key name, pressed and released, by building an event and decoding it again; they never post one.
• End to end in a VM: two systemKeyStroke("SOUND_UP") calls raised the output volume from 50 to 63, and a systemDefined watcher decoded all four down/up events.
• npm run docs:generate and docs:test pass.

🤖 Generated with Claude Code

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge, with the previous testing concern addressed.

Summary

Adds system-key support to hs.eventtap.

• Scripts can build and send named system-key events.
• Watchers can read which system key was pressed or released.

Since the last review, only tests changed. The new fixtures address the previous request for repeat, unknown-code, and other-subtype coverage. No new actionable issues were found.

_{Reviews (2) · Last reviewed commit: "Test the system key decoder against hand..." · Reviewed by Greptile}

[cmsj]

@greptile