fix: restore native window controls

[arzafran]

What this does

Keeps shortcut badges compact and returns traffic-light layout and visibility to AppKit so the controls stay stable through resize, fullscreen, and titlebar changes.

Review order

1. The shortcut hint pill now sizes to its intrinsic content.
2. The custom traffic-light frame writer and its lifecycle callbacks are removed.
3. The regression test verifies that a lifecycle notification cannot translate AppKit's native buttons.

Test plan

• Tagged Debug build: native-window-controls
• Regression test recorded red before the production fix in CI run 31849184894
• Corrected branch CI run 31852193167