Phase 6: QA fixes for Lighthouse and navigation

- Map is a titled iframe (accessibility); drop @next/third-parties
- "Services" nav toggle is a real button with aria-expanded (SEO
  crawlable-anchors, accessibility)
- Hero images use default quality; page-header image is preloaded (LCP)
- Mobile services submenu no longer clips its last item

Mobile Lighthouse: / 94/100/100/100, /services/computer-repair
96/100/100/100, /areas/henderson 97/100/100/100, /contact 95/100/100/100
(performance/accessibility/best practices/SEO).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

package.json

@@ -10,7 +10,6 @@
   },
   "dependencies": {
     "@next/env": "^16.2.10",
-    "@next/third-parties": "^16.2.10",
     "@radix-ui/react-accordion": "^1.2.3",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",