fix(ui): Fix regression on Shift-Backspace not being handled (#454)

This keystroke is valid and means "delete to the right" on MacOS.

Author: IDisposable

ui/src/keyboardMappings.ts

@@ -243,6 +243,7 @@ export const keyDisplayMap: Record<string, string> = {
   Escape: "esc",
   Tab: "tab",
   Backspace: "backspace",
+  "(Backspace)": "backspace",
   Enter: "enter",
   CapsLock: "caps lock",
   ShiftLeft: "shift",