feat: glitter sparkles on heart, metallic gold text across all headings

- Add animated gold sparkle dots on heart surface with glow filter
- Brighten heart metal fill for better visibility against dark bg
- Update headline gradient to dark metallic gold (no white tones)
- Apply gradient-text to all section headings for consistency
- Warm gold subtitle color in hero

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

src/components/ui/SectionHeading.tsx

@@ -8,7 +8,7 @@ export function SectionHeading({ children, className = "", centered = false }: S
   return (
     <div className={centered ? "text-center" : ""}>
       <h2
-        className={`font-display text-4xl font-bold uppercase tracking-wide sm:text-5xl lg:text-6xl heading-text ${className}`}
+        className={`font-display text-4xl font-bold uppercase tracking-wide sm:text-5xl lg:text-6xl gradient-text ${className}`}
       >
         {children}
       </h2>