Bug: Autofocus is lost when a deferred GPU window is first shown on macOS

On macOS, an autofocus widget mounted inside a GPU window may not receive keyboard focus when the window uses .on_first_present.

Reproduction:

1. Mount a textarea with autofocus = true in the initial layout.
2. Launch the app with a deferred GPU window.
3. After the first frame appears, type without clicking the textarea.

Expected: the textarea receives the input.

Actual: AXFocusedUIElement is the window, not the textarea.

The autofocus request runs while the window is still ordered out. Later, showDeferredWindowIfPending calls makeKeyAndOrderFront, but does not restore the requested first responder. Because autofocus is edge-triggered, subsequent rebuilds do not retry it.

Suggested fix: retain the pending focused NSView for deferred windows and call makeFirstResponder after makeKeyAndOrderFront. Please add a macOS regression test covering autofocus through the initial deferred-show transition.

Trace the deferred-window path around showDeferredWindowIfPending and the autofocus request for the initial layout. Add a macOS regression test covering autofocus when a GPU window is first shown with .on_first_present. Done means the textarea receives keyboard input without a click after the first frame appears.