test(visual): add authenticated about-mobile snapshot

Add about to authenticatedMobilePages to capture an authenticated baseline
needed for regression detection during the Phase 3.5 about.vue migration.

Rename all auth-mobile snapshots from *-mobile to *-mobile-auth to avoid
name collision with the public loop's about-mobile snapshot.

e2e/visual/pages.spec.js

@@ -32,9 +32,10 @@ const authenticatedPages = [
 
 // Pages that need mobile coverage captured while authenticated.
 // These cover column-collapse breakpoints critical for the page-shell refactor.
-// Note: 'about' mobile is already captured by the public pages loop (no auth middleware),
+// Snapshots use the -mobile-auth suffix to distinguish from the public mobile loop
-// so it is not duplicated here to avoid snapshot name collisions.
+// (which also captures about-mobile unauthenticated, so names must not collide).
 const authenticatedMobilePages = [
+  { name: 'about', path: '/about' },
   { name: 'member-dashboard', path: '/member/dashboard' },
   { name: 'member-profile', path: '/member/profile' },
   { name: 'member-account', path: '/member/account' },
@@ -163,7 +164,7 @@ test.describe('visual regression', () => {
         await page.goto(path)
         await waitForStable(page)
 
-        await expect(page).toHaveScreenshot(`${name}-mobile.png`, {
+        await expect(page).toHaveScreenshot(`${name}-mobile-auth.png`, {
           maxDiffPixelRatio: 0.01,
           mask: commonMasks(page),
         })