[codex] hide decorative social share icons

[Sean-Kenneth-Doherty]

Summary

• Mark the inline social-share SVG icons as decorative with aria-hidden="true" and focusable="false".

Why

Each social share card already has visible text that names the destination, so the SVGs should not add extra noise to assistive technology output.

Validation

• pnpm build
• Confirmed built dist/index.html renders all three social SVGs with aria-hidden="true" and focusable="false"
• git diff --check

Contributes to #347.

[Sean-Kenneth-Doherty]

Fresh validation against the current PR head (096019d):

• the PR is scoped to src/components/SocialShare.astro
• the three social-share SVG icons are marked aria-hidden="true" and focusable="false"
• the share links and visible text labels remain in place for Twitter, Facebook, and LinkedIn
• GITHUB_TOKEN=$(gh auth token) pnpm build -> Astro build succeeded, 2 pages
• generated dist/index.html contains the social-share section, 3 share links, 3 visible labels, and 3 decorative SVGs hidden from assistive tech
• git diff --check origin/main...HEAD -> clean

I validated this in an isolated temporary git worktree so generated .astro/dist output did not touch the main checkout.