fix(marketing): A-2.7b WCAG 2.2 AA polish + JSON-LD test hardening

- Drop role="region" from FAQ panels (had no accessible name — axe-core
  violation; disclosure pattern with button + aria-controls + aria-expanded
  is sufficient per WAI-APG accordion guidance)
- Add focus-visible:outline-2 outline-brand-b1 outline-offset-2 to FAQ
  buttons (WCAG 2.2 AA 2.4.7 Focus Not Obscured + 2.4.11 Focus Appearance —
  Safari default focus indicator is unreliable)
- Sweep pre-existing text-white/50 on Hero social proof microcopy → /70
  (branch-wide WCAG floor; recurring landmine flagged at A-2.7a review)
- Strengthen test_faq_jsonld_schema_present to json.loads() the extracted
  block and validate the FAQPage schema shape (regression guard for future
  content edits with unescaped backslashes/quotes)

static/css/marketing.css

@@ -3701,6 +3701,22 @@
       outline-style: none;
     }
   }
+  .focus-visible\:outline-2 {
+    &:focus-visible {
+      outline-style: var(--tw-outline-style);
+      outline-width: 2px;
+    }
+  }
+  .focus-visible\:outline-offset-2 {
+    &:focus-visible {
+      outline-offset: 2px;
+    }
+  }
+  .focus-visible\:outline-brand-b1 {
+    &:focus-visible {
+      outline-color: #0062ff;
+    }
+  }
   .active\:scale-95 {
     &:active {
       --tw-scale-x: 95%;