The browser portal's hit-test was intercepting clicks in the titlebar
region, preventing double-click-to-zoom from reaching the window.
Three fixes:
- BrowserWindowPortal: pass through hits landing in the native titlebar
- WindowDragHandleView: only let titlebar-overlay views block capture,
not underlay browser content; respect AppleActionOnDoubleClick pref
- ContentView: use shared performStandardTitlebarDoubleClick() helper
Closes https://github.com/manaflow-ai/cmux/issues/422
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>