perf: cut CI time, fix CSS chain, fix iPad hero layout, fix contrast

CI:
- Replace `npm run build` with `tsc --noEmit` in test-build job
  → eliminates duplicate Next.js build (~5 min saved per push)
  → Docker deploy job already does the full build

PageSpeed:
- Add `cssChunking: 'loose'` to merge CSS into one chunk and break
  the 84dc7384→3aefc04b render-blocking CSS waterfall chain (450ms mobile)
- Remove @shadergradient/react, @react-three/fiber, three from
  package.json — packages were already unused in code, removes any
  residual bundling risk for chunk 7001

Hero:
- Change lg:flex-row → xl:flex-row so iPad (1024px) stays in column
  layout; the 9.5rem heading overflowed into the image at lg causing
  the photo to be clipped by overflow-hidden on the section
- Update image sizes attribute to match new xl breakpoint
- Fix contrast: "GET IN TOUCH" link text-stone-500 → text-stone-700
  (contrast 3.7:1 → 7:1, now WCAG AA compliant)
- Change text-center/justify-center to xl: variants to match layout

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -33,8 +33,8 @@ jobs:
       - name: Test
         run: npm run test
 
-      - name: Build
-        run: npm run build
+      - name: Type check
+        run: npx tsc --noEmit
 
   # ── Job 2: Deploy to dev (only on dev branch, after tests pass) ──
   deploy-dev: