style(landing): restyle mobile hero CTAs as stacked filled buttons

Match the Claude Code product page: full-width stacked buttons with a dark
filled GitHub primary and a light filled Star secondary, replacing the
side-by-side ghost buttons.

Author: misonijnik

src/components/AnimatedHero.tsx

@@ -43,12 +43,12 @@ export function AnimatedHero() {
         AST-pattern rules. Whole-program taint analysis. Formal substrate for AI application security.
       </p>
 
-      <div className="mt-8 flex justify-center gap-3 sm:hidden">
+      <div className="mt-8 flex flex-col gap-3 sm:hidden">
         <a
           href="https://github.com/seqra/opentaint#quick-start"
           target="_blank"
           rel="noopener noreferrer"
-          className="inline-flex items-center gap-2 rounded border border-border bg-secondary/50 px-4 min-h-11 font-mono text-xs uppercase tracking-[0.14em] text-foreground/80 transition-colors hover:border-border-strong hover:text-foreground"
+          className="inline-flex w-full items-center justify-center gap-2 rounded-lg bg-foreground px-4 py-3 font-mono text-[15px] font-medium text-background transition-colors hover:bg-foreground/85"
         >
           <svg role="img" viewBox="0 0 98 96" xmlns="http://www.w3.org/2000/svg" className="h-4 w-4" fill="currentColor" aria-hidden="true">
             <path d="M48.854 0C21.839 0 0 22 0 49.217c0 21.756 13.993 40.172 33.405 46.69 2.427.49 3.316-1.059 3.316-2.362 0-1.141-.08-5.052-.08-9.127-13.59 2.934-16.42-5.867-16.42-5.867-2.184-5.704-5.42-7.17-5.42-7.17-4.448-3.015.324-3.015.324-3.015 4.934.326 7.523 5.052 7.523 5.052 4.367 7.496 11.404 5.378 14.235 4.074.404-3.178 1.699-5.378 3.074-6.6-10.839-1.141-22.243-5.378-22.243-24.283 0-5.378 1.94-9.778 5.014-13.2-.485-1.222-2.184-6.275.486-13.038 0 0 4.125-1.304 13.426 5.052a46.97 46.97 0 0 1 12.214-1.63c4.125 0 8.33.571 12.213 1.63 9.302-6.356 13.427-5.052 13.427-5.052 2.67 6.763.97 11.816.485 13.038 3.155 3.422 5.015 7.822 5.015 13.2 0 18.905-11.404 23.06-22.324 24.283 1.78 1.548 3.316 4.481 3.316 9.126 0 6.6-.08 11.897-.08 13.526 0 1.304.89 2.853 3.316 2.364 19.412-6.52 33.405-24.935 33.405-46.691C97.707 22 75.788 0 48.854 0z" />
@@ -60,7 +60,7 @@ export function AnimatedHero() {
           target="_blank"
           rel="noopener noreferrer"
           aria-label="Star opentaint on GitHub"
-          className="inline-flex items-center gap-2 rounded border border-border bg-secondary/50 px-4 min-h-11 font-mono text-xs uppercase tracking-[0.14em] text-foreground/80 transition-colors hover:border-border-strong hover:text-foreground"
+          className="inline-flex w-full items-center justify-center gap-2 rounded-lg bg-secondary px-4 py-3 font-mono text-[15px] font-medium text-foreground transition-colors hover:bg-border"
         >
           <Star className="h-4 w-4" aria-hidden="true" />
           Star