[addhumal]

Part of #272. Split from #293, which keeps the iPhone's arrow keys (#287): one change per pull request.

What it does

• The Keys menu: a long press on the Keyboard button, on every bar (the landscape bar, a phone's row 1, the iPad's key-row cap).
  • Mac: Lock Screen (⌃⌘Q), Force Quit… (⌥⌘⎋), Screenshot… (⇧⌘5), Switch to the Last App (⌘⇥).
  • Window (Window tiling shortcuts in Desktop mode #272): Left, Right, Top and Bottom Half; Fill; Center; Return to Previous Size. These are macOS 15's own Globe-Control shortcuts, shown only for a Mac that says it takes fn.
• Host: a device's fn bit (bit 23, the Globe key) now reaches the Mac as maskSecondaryFn. UIKit has no fn flag, so only these shortcuts set it. The window list gains an additive fnKey, sent only from macOS 15 (KeyStrokes.fnKey).

Checks

• key-strokes: 522 checks. Each shortcut goes through the host's own KeyStrokes, and its key goes down with exactly its chord, with nothing held after. Its mutants (146 of 146) were run on Keys: the iPhone's arrow keys, a second page of the key row (#287) #293; the checked files are the same here, so they weren't run again.
• compatibility: 154 checks (36 of 36 mutants on Keys: the iPhone's arrow keys, a second page of the key row (#287) #293, the same files).
• swift build -c release: only the CaptureProbe warning. The iOS app for the simulator: only the known StreamClient warning.

What I tried

• On a 14-inch MacBook Pro (M4 Pro, macOS 27.0.1), Xcode 27.2: the checks and builds above. Not on a device.

Problems found, and how they were fixed

• From Keys: the iPhone's arrow keys, a second page of the key row (#287) #293's review: tiling on macOS 14 would have switched Spaces. macOS gives every arrow key fn already, so fn⌃← arrives as ⌃←, the Space on the left. Fix: fnKey only from macOS 15, so the menu hides the tiling elsewhere.

Not checked

• The shortcuts on a real Mac: whether macOS 15+ tiles from a posted Globe-Control chord, and Lock Screen, Force Quit and Screenshot.
• The long press on a device, and VoiceOver.