fix(desktop): add MoA preset enabled toggle

Salvaged from PR #59743. Original author email was malformed
(sr@samirusani, not resolvable to a GitHub account), so the commit is
re-authored with credit via trailer.

Co-authored-by: Sami Rusani <samrusani@users.noreply.github.com>

apps/desktop/src/app/settings/model-settings.test.tsx

@@ -435,4 +435,25 @@ describe('ModelSettings MoA preset editor', () => {
       vi.useRealTimers()
     }
   })
+
+  it('autosaves the selected preset when its enabled switch is toggled', async () => {
+    vi.useFakeTimers({ shouldAdvanceTime: true })
+
+    try {
+      await openReferenceEditor()
+
+      fireEvent.click(screen.getByRole('switch', { name: 'Enabled' }))
+      await vi.advanceTimersByTimeAsync(700)
+
+      expect(saveMoaModels).toHaveBeenCalledWith(
+        expect.objectContaining({
+          presets: expect.objectContaining({
+            default: expect.objectContaining({ enabled: false })
+          })
+        })
+      )
+    } finally {
+      vi.useRealTimers()
+    }
+  })
 })

apps/desktop/src/app/settings/model-settings.tsx

@@ -993,6 +993,15 @@ export function ModelSettings({ onMainModelChanged }: ModelSettingsProps) {
                 ))}
               </SelectContent>
             </Select>
+            <label className="flex items-center gap-2 rounded-sm border border-border px-2 py-1 text-xs">
+              Enabled
+              <Switch
+                checked={currentMoaPreset.enabled !== false}
+                disabled={applying}
+                onCheckedChange={checked => updateMoaPreset(prev => ({ ...prev, enabled: checked }))}
+                size="xs"
+              />
+            </label>
             <Button
               disabled={applying}
               onClick={() => {