Mousetrap matched keydown shortcuts against event.key, the glyph the
key types, but bindings name the key. Modifiers change the glyph: on
any OS with a US layout Shift+0 types ")" and Shift+5 types "%", and
macOS Option changes it further (Option+Shift+5 types "fi", Option+A
types "å"). So shortcuts like Alt+Shift+5 for strikethrough or
Shift+0/1/2 for zoom never fired, on every platform. Read letters and
digits from keyCode on keydown, and record them the same way when a
modifier is held.
Closes#12217
AI-assisted-by: claude-opus-5-5
21ecfb67b7