Add storefront component migration: cards, badges, progress bars, animations, and React wrapper package

Major feature migration from dt-shopify-storefront into the design system:

- Card system: per-card color modes (normal/emphasis/warning/success/other),
  progress bars, full-bleed card body (card-body-flush), image bevel clip-paths,
  and visible structural borders at bevel corners
- Badge system: dt-card-badge with position-aware offsets for cards vs media frames
- Media frames: dt-bevel-media with inner surface fill, image clipping, and
  "MISSING MEDIA" placeholder for empty containers
- Interactive bevel buttons: dt-btn with hover/selected states and pulse animation
- Menu items: dt-menu-item with active states and level indentation
- Animations: scale-in, fade-in, slide-up, pulse, ping, spin keyframes
- Feature legend: CSS grid for product feature icons with state colors
- Scrollbar styling for DT brand
- New @dangerousthings/react package wrapping web CSS components
- New @dangerousthings/tailwind-preset package
- New @dangerousthings/hex-background package
- Desktop showcase rewritten in React with Tailwind CSS
- Mobile showcase updated with new screens (animations, filters, advanced cards)
- Tokens: added mode color tokens, RGB variants, and selected-state tokens

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

packages/react/src/components/DTGallery.tsx

@@ -0,0 +1,91 @@
+/**
+ * DTGallery — Image gallery with beveled media frame and thumbnails.
+ *
+ * CSS reference: bevels.css .dt-bevel-media
+ */
+
+import { useState, type CSSProperties } from 'react';
+import type { DTVariant } from '@dangerousthings/tokens';
+import { cx } from '../utils/cx';
+import { getVariantClass } from '../utils/variantClasses';
+
+export interface DTGalleryItem {
+  key: string;
+  src: string;
+  alt?: string;
+  thumbnail?: string;
+}
+
+interface DTGalleryProps {
+  items: DTGalleryItem[];
+  /** Color variant @default 'normal' */
+  variant?: DTVariant;
+  className?: string;
+  style?: CSSProperties;
+}
+
+export function DTGallery({
+  items,
+  variant = 'normal',
+  className,
+  style,
+}: DTGalleryProps) {
+  const [activeIndex, setActiveIndex] = useState(0);
+
+  if (items.length === 0) return null;
+
+  const current = items[activeIndex];
+
+  return (
+    <div className={cx(getVariantClass(variant), className)} style={style}>
+      {/* Main image */}
+      <div className="dt-bevel-media" style={{ overflow: 'hidden' }}>
+        <img
+          src={current.src}
+          alt={current.alt || ''}
+          style={{
+            width: '100%',
+            height: 'auto',
+            display: 'block',
+            transition: 'opacity 300ms ease-in-out',
+          }}
+        />
+      </div>
+      {/* Thumbnails */}
+      {items.length > 1 && (
+        <div
+          style={{
+            display: 'flex',
+            gap: '8px',
+            marginTop: '8px',
+            overflowX: 'auto',
+          }}>
+          {items.map((item, i) => (
+            <button
+              key={item.key}
+              onClick={() => setActiveIndex(i)}
+              type="button"
+              style={{
+                flexShrink: 0,
+                width: '64px',
+                height: '64px',
+                padding: 0,
+                border: i === activeIndex
+                  ? '2px solid var(--dt-card-color, var(--color-primary))'
+                  : '2px solid transparent',
+                background: 'none',
+                cursor: 'pointer',
+                overflow: 'hidden',
+              }}>
+              <img
+                src={item.thumbnail || item.src}
+                alt={item.alt || ''}
+                style={{ width: '100%', height: '100%', objectFit: 'cover' }}
+              />
+            </button>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}