The surface's onResize callback is now the only PTY resize channel, so
fit() must fire it on the first successful measure even when the real
grid equals the 1x1 construction sentinel. Key-release suppressions now
survive blur: a shortcut that moves focus away must still swallow its
own keyup when focus returns, and stale entries are already harmless
because an encoding keydown removes its code first.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>