Escape was a leftover spike convenience that quit the tool. Esc is a common
in-game key, so dropping it from a borderless mirror was too easy to do by
accident. Remove the Escape-quit handler and add a File -> Exit menu item
(shown with its Alt+F4 shortcut). Alt+F4 already worked via DefWindowProc ->
WM_CLOSE -> WM_DESTROY; the menu item sets a one-shot flag the main loop reads.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>