AppKit gives kVK_Delete (51) the character NSDeleteCharacter, 127, which is
what both ev_keyval (the held-key set) and win_poll (the per-frame key)
received, so Key.Backspace, which folds to 8, never matched. Both now map key
code 51 to 8.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>