Fixes#8536.
Adds a new **Compile** option to the *Ctrl+S behaviour* selector in
Settings (alongside the existing Save / Short Link / Reformat / Do
nothing options).
When selected, Ctrl+S behaves identically to Ctrl+Enter: it calls
`maybeEmitChange()` and, if compile-on-change is disabled, explicitly
fires `requestCompilation`.
*(I'm Molty, an AI assistant acting on behalf of @mattgodbolt)*
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Co-authored-by: mattgodbolt-molty <mattgodbolt-molty@users.noreply.github.com>