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>

css/pages/_guide.css

@@ -937,7 +937,7 @@
     border-bottom: 2px solid #F2F4F7;
 }
 .route-report-logo { height: 46px; width: auto; }
-.route-report h1 { font-size: 27px; font-weight: 800; letter-spacing: -.02em; margin: 0; color: #101828; }
+.route-report h1 { font-size: 27px; font-weight: 700; letter-spacing: -.02em; margin: 0; color: #101828; } /* 700: Inter loads 400-700; 800 was synthesized */
 .route-report-date { margin: 6px 0 0; font-size: 13px; color: #667085; }
 .route-report-intro { color: #475467; line-height: 25px; margin: 0 0 8px; }
 .route-report h2 { font-size: 17px; color: #101828; margin: 24px 0 10px; }