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/media/MapEmbed.toHtml.test.ts

@@ -0,0 +1,16 @@
+import { describe, test, expect } from 'vitest';
+import { MapEmbed } from './MapEmbed';
+
+const toHtml = (MapEmbed as any).toHtml;
+
+describe('MapEmbed.toHtml iframe accessibility (F2.4)', () => {
+  test('iframe has a non-empty title attribute', () => {
+    const { html } = toHtml({ address: 'New York, NY' }, '');
+    expect(html).toMatch(/<iframe[^>]*title="[^"]+"/);
+  });
+
+  test('title reflects the configured address', () => {
+    const { html } = toHtml({ address: 'Golden Gate Bridge' }, '');
+    expect(html).toContain('title="Map of Golden Gate Bridge"');
+  });
+});