perf: Lighthouse and Core Web Vitals optimizations (#22)

[abbys-code-hub]

Closes wraith-protocol#22

This PR introduces critical performance and core web vitals optimizations for the landing page, raising all Lighthouse scores to 95+ (specifically achieving 99-100 on all axes on mobile and desktop).

Optimizations Performed:

1. Typography & Font Preloading: Self-hosted Space Grotesk, Inter, and JetBrains Mono fonts as local .woff2 variable assets, setting font-display: swap and preloading critical font files to avoid render-blocking CDN network requests.
2. CSS Inlining: Developed a custom Vite plugin to inline built CSS directly into index.html, eliminating stylesheet network requests entirely.
3. Image Optimization: Converted logo.png to WebP, resized it from 1288x1020 to 120x95 (saving 92% file size), and set explicit width/height attributes for logos and SVGs to prevent cumulative layout shifts (CLS).
4. Landmark & Contrast Fixes: Added a <main> container for better screen-reader landmarks. Tweaked --color-outline to #858585 to satisfy the WCAG AA 4.5:1 text color contrast requirements.
5. Bots / Crawling Compliance: Added standard /robots.txt and /llms.txt config files.
6. PR CI Automation: Configured a Lighthouse audit job in .github/workflows/ci.yml that comments on PRs with mobile and desktop performance reports.

Local Audit Results (Post-Optimization):

• Mobile: Performance 99 | Accessibility 100 | Best Practices 100 | SEO 100
• Desktop: Performance 100 | Accessibility 100 | Best Practices 100 | SEO 100