test(e2e): scope the dashboard rail link check to the workspace rail

The rail-toggle settings test asserted on getByRole('link', { name:
'Dashboard' }), which also matches the settings section nav's own
"Dashboard" link. #1709 added waits for the settings view to unmount
first; scope the locator to .portal-rail-link as well so the assertion
cannot resolve to the settings link at all.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/electron-backend-e2e/src/settings.e2e.ts

@@ -715,10 +715,9 @@ test.describe('Electron Settings', () => {
                 app.mainWindow.getByTestId('dashboard-recent-sources-rail')
             ).toHaveCount(0);
             await expect(
-                app.mainWindow.getByRole('link', {
-                    name: 'Dashboard',
-                    exact: true,
-                })
+                app.mainWindow
+                    .getByRole('link', { name: 'Dashboard', exact: true })
+                    .and(app.mainWindow.locator('.portal-rail-link'))
             ).toBeVisible();
         } finally {
             await closeElectronApp(app);