perf: optimize Lighthouse scores to 100

Performance:
- Lazy-load ShaderGradientBackground via dynamic import (reduces initial JS ~250KB)
- Disable ShaderGradient animations (animate=off) to reduce CPU/GPU load
- Remove opacity:0 animations from Hero LCP elements for instant paint
- Add browserslist targeting modern browsers (eliminates ~13KB polyfills)

Accessibility:
- Fix color contrast: text-stone-400 → text-stone-600 dark:text-stone-400 on light backgrounds
- Fix text-liquid-mint → text-emerald-700/600 for readable text/accent dots
- Fix quote text contrast on dark status box (text-stone-700 → text-stone-300)
- Fix Online badge contrast (emerald-600 → emerald-700)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

app/components/ActivityFeed.tsx

@@ -134,7 +134,7 @@ export default function ActivityFeed({
               transition={{ duration: 0.5 }}
               className="space-y-4"
             >
-              <p className="text-base sm:text-lg md:text-xl lg:text-2xl font-light leading-tight text-stone-700 dark:text-stone-300 italic">
+              <p className="text-base sm:text-lg md:text-xl lg:text-2xl font-light leading-tight text-stone-300 italic">
                 &ldquo;{allQuotes[quoteIndex].content}&rdquo;
               </p>
               <p className="text-xs font-black text-stone-400 dark:text-stone-500 uppercase tracking-widest">