style(qa3): design-token foundation + safe polish/a11y fixes

- Add :root design tokens in _typography.css (was empty) — brand teal/orange,
  ink/text greys, radius + type scale + section rhythm. Visually neutral;
  new rules can reference var()s instead of scattered literals.
- a11y: visible :focus-visible ring on header nav + dropdown links (keyboard
  users had none).
- Fix synthesized faux-bold: .route-report h1 800 -> 700 (Inter loads 400-700).
- Testimonials column: overflow-y scroll -> auto (no permanent scrollbar gutter).
- Lightbox image radius 6px -> 8px (matches the site rounding scale).
- Consistent card affordance: homepage .news-card now lifts on hover like the
  news-hub / blog cards.
- Re-stamped cache-bust (v=1f64b22f).

Deferred (needs a brand decision): unifying the two primary oranges
(#FA7850 vs #F2762E) and the fuller literal->token migration.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

404.html

@@ -25,7 +25,7 @@
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
     <link href="https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap" rel="stylesheet">
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.1/css/all.min.css" crossorigin="anonymous" referrerpolicy="no-referrer">
-    <link rel="stylesheet" href="/css/main.css?v=6770822f">
+    <link rel="stylesheet" href="/css/main.css?v=1f64b22f">
 
     <link rel="icon" type="image/png" href="/favicon-96x96.png" sizes="96x96">
     <link rel="icon" type="image/svg+xml" href="/favicon.svg">
@@ -70,7 +70,7 @@
             </p>
         </div>
     </main>
-<link rel="stylesheet" href="/assistant.css?v=6770822f">
-<script src="/assistant.js?v=6770822f" defer></script>
+<link rel="stylesheet" href="/assistant.css?v=1f64b22f">
+<script src="/assistant.js?v=1f64b22f" defer></script>
 </body>
 </html>