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/DTCard.tsx

@@ -0,0 +1,66 @@
+/**
+ * DTCard — Beveled card with header, progress bar, and mode colors.
+ *
+ * CSS reference: bevels.css .card / .dt-bevel-card, .card-title,
+ * ::after progress bar, .mode-*
+ *
+ * The progress bar is a structural element on the left edge (0 to bevel-sm).
+ * It is always present. At 0 progress it shows surface color (empty bar).
+ * As progress increases, accent color fills from the bottom up.
+ */
+
+import type { ReactNode, CSSProperties } from 'react';
+import type { DTVariant } from '@dangerousthings/tokens';
+import { cx } from '../utils/cx';
+import { getVariantClass } from '../utils/variantClasses';
+
+interface DTCardProps {
+  children: ReactNode;
+  /** Color variant @default 'normal' */
+  variant?: DTVariant;
+  /** Card title (displayed in header bar) */
+  title?: string;
+  /** Whether to show the accent header bar @default true when title is provided */
+  showHeader?: boolean;
+  /** Progress value (0–100) for left-edge vertical progress bar @default 0 */
+  progress?: number;
+  className?: string;
+  style?: CSSProperties;
+  onClick?: () => void;
+}
+
+export function DTCard({
+  children,
+  variant = 'normal',
+  title,
+  showHeader,
+  progress = 0,
+  className,
+  style,
+  onClick,
+}: DTCardProps) {
+  const shouldShowHeader = showHeader ?? !!title;
+  const Tag = onClick ? 'button' : 'div';
+
+  return (
+    <Tag
+      className={cx(
+        'card',
+        getVariantClass(variant),
+        className,
+      )}
+      style={{
+        ...style,
+        '--dt-card-progress': progress,
+      } as CSSProperties}
+      onClick={onClick}
+      type={onClick ? 'button' : undefined}>
+      {shouldShowHeader && (
+        <div className="card-title">
+          {title}
+        </div>
+      )}
+      {children}
+    </Tag>
+  );
+}