Add animated mesh gradient hero with overlay content

- Add @paper-design/shaders for WebGL mesh gradient effect
- Create hero-shader.js with liquid ink gradient (grayscale palette)
- Add overlay content: title, tagline, and CTA on shader
- Update hero section structure and styling
- Fix accessibility: gallery dot buttons, toggle ARIA attributes
- Fix undefined --color-terracotta CSS variable
- Update distribution structure for Codex/Cursor skills

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

public/css/gallery.css

@@ -158,6 +158,9 @@
   cursor: pointer;
   transition: all 0.3s ease;
   position: relative;
+  border: none;
+  padding: 0;
+  font: inherit;
 }
 
 .gallery-dot::after {
@@ -169,6 +172,12 @@
   right: 0;
 }
 
+.gallery-dot:focus-visible {
+  outline: 2px solid var(--color-accent);
+  outline-offset: 4px;
+  border-radius: 1px;
+}
+
 .gallery-dot.active {
   background: var(--color-accent);
   height: 4px;