fix(settings): restore <pre>{pretty}</pre> block in export preview modal

The <pre> element that renders the JSON content was missing from
the modal, leaving the operator looking at section counts and
buttons with an empty body. Restored the element with the same
classes used elsewhere in the modal:

  - flex-1 min-h-0: takes the remaining vertical space inside
    the modal's flex column
  - overflow-auto: scrollable when the JSON is larger than the
    viewport
  - whitespace-pre-wrap break-all: wraps very long lines so
    individual fallback entries or model rows don't force a
    horizontal scroll
  - text-[11px] font-mono leading-snug: matches the rest of
    the modal's code-style chrome

Author: MLuqmanBR

client/src/pages/SettingsPage.tsx

@@ -625,6 +625,9 @@ function ExportPreviewModal({
             </span>
           )}
         </div>
+        <pre className="flex-1 min-h-0 overflow-auto rounded-lg border bg-muted/30 p-3 text-[11px] font-mono leading-snug whitespace-pre-wrap break-all">
+          {pretty}
+        </pre>
         <div className="flex justify-end gap-2 mt-3">
           <Button
             variant="outline"