One Check every feed button: the top bar's (#416)

All Subscriptions' header had its own, beside Mark everything read, doing
what the top bar's Refresh does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RqkrVDqdiQEMWAkNGQ2tYA

tests/ui/app.spec.ts

@@ -1549,6 +1549,10 @@ test('All Subscriptions marks everything read, across every feed', async ({ page
   await expect(page.locator('#detail [data-a="read"][title="Mark read"]')).toBeVisible();
   await expect(all.locator('.badge')).not.toHaveText('0');
 
+  // Checking every feed is the top bar's alone; the header had a second button for it (#416).
+  await expect(page.locator('#content .acts button')).toHaveCount(1);
+  await expect(page.locator('#scanAll')).toBeVisible();
+
   page.once('dialog', d => d.accept());
   await page.locator('#content .acts [data-a="readall"]').click();
   await expect(all.locator('.badge')).toHaveText('0');