The /hotkeys table described app.exit (Ctrl+D) as "Exit (when editor is
empty)", implying readline/EOF-style conditional exit. The handler exits
unconditionally and snapshots the current prompt as a resumable draft
regardless of editor content (custom-editor.ts fires onExit for app.exit
with no empty check; input-controller.ts handleCtrlD calls shutdown()
unconditionally, which persists the draft). Corrected the line to
"Exit (saves current prompt as draft)".
Fixes#8530