a11y: exported semantics (forms/rating/nav/iframe/icons)

- InputField/TextareaField/ContactForm: every control gets a
  deterministic id (slugId() in utils/escape.ts, derived from the
  field's name/label + index for ContactForm's looped fields -- no
  Math.random) with a matching <label for=>; fields with no visible
  label get an aria-label from the placeholder/name instead.
- StarRating: wrapped in role="img" aria-label="Rating: N out of M",
  individual star glyphs marked aria-hidden.
- Navbar: the mobile hamburger toggle gets aria-label="Toggle
  navigation menu", aria-controls="navbar-links", and aria-expanded
  wired to flip true/false in the inline onclick handler.
- VideoBlock and MapEmbed: every exported <iframe> gets a title
  (generic "Embedded video", or "Map of {address}" for MapEmbed).
- Decorative Font Awesome icons (ContentSlider arrows already covered
  in the prior commit; SocialLinks, SearchBar, Testimonials stars) are
  aria-hidden; SocialLinks' icon-only links get an aria-label naming
  the platform alongside the existing title tooltip.

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

craft/src/components/sections/Testimonials.tsx

@@ -42,9 +42,9 @@ function renderStars(count: number, color: string): React.ReactNode {
 
 function starsHtml(count: number, color: string): string {
   const stars = [1, 2, 3, 4, 5].map((i) =>
-    `<i class="fa ${i <= count ? 'fa-star' : 'fa-star-o'}" style="color:${color};font-size:14px"></i>`
+    `<i class="fa ${i <= count ? 'fa-star' : 'fa-star-o'}" style="color:${color};font-size:14px" aria-hidden="true"></i>`
   ).join('');
-  return `<div style="display:flex;gap:2px;justify-content:center;margin-bottom:12px">${stars}</div>`;
+  return `<div style="display:flex;gap:2px;justify-content:center;margin-bottom:12px" role="img" aria-label="Rating: ${count} out of 5">${stars}</div>`;
 }
 
 export const Testimonials: UserComponent<TestimonialsProps> = ({