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/DTModal.tsx

@@ -0,0 +1,96 @@
+/**
+ * DTModal — Portal-based modal with beveled card content.
+ *
+ * CSS reference: bevels.css .dt-bevel-modal, .card, .mode-*
+ */
+
+import { useEffect, useCallback, type ReactNode, type CSSProperties } from 'react';
+import { createPortal } from 'react-dom';
+import type { DTVariant } from '@dangerousthings/tokens';
+import { cx } from '../utils/cx';
+import { getVariantClass } from '../utils/variantClasses';
+
+interface DTModalProps {
+  visible: boolean;
+  onDismiss: () => void;
+  title?: string;
+  /** Color variant @default 'normal' */
+  variant?: DTVariant;
+  children: ReactNode;
+  /** Whether clicking backdrop dismisses @default true */
+  dismissable?: boolean;
+  className?: string;
+  style?: CSSProperties;
+}
+
+export function DTModal({
+  visible,
+  onDismiss,
+  title,
+  variant = 'normal',
+  children,
+  dismissable = true,
+  className,
+  style,
+}: DTModalProps) {
+  const handleKeyDown = useCallback(
+    (e: KeyboardEvent) => {
+      if (e.key === 'Escape' && dismissable) onDismiss();
+    },
+    [onDismiss, dismissable],
+  );
+
+  useEffect(() => {
+    if (visible) {
+      document.addEventListener('keydown', handleKeyDown);
+      return () => document.removeEventListener('keydown', handleKeyDown);
+    }
+  }, [visible, handleKeyDown]);
+
+  if (!visible) return null;
+
+  return createPortal(
+    <div
+      className="dt-modal-overlay"
+      style={{
+        position: 'fixed',
+        inset: 0,
+        display: 'flex',
+        alignItems: 'center',
+        justifyContent: 'center',
+        zIndex: 1000,
+      }}>
+      <div
+        className="dt-modal-backdrop"
+        style={{
+          position: 'absolute',
+          inset: 0,
+          background: 'rgba(0, 0, 0, 0.5)',
+          backdropFilter: 'blur(4px)',
+        }}
+        onClick={dismissable ? onDismiss : undefined}
+      />
+      <div
+        className={cx(
+          'card',
+          'dt-bevel-modal',
+          getVariantClass(variant),
+          'dt-animate-scale-in',
+          className,
+        )}
+        style={{
+          position: 'relative',
+          maxWidth: '90vw',
+          maxHeight: '85vh',
+          overflow: 'auto',
+          ...style,
+        }}
+        role="dialog"
+        aria-modal="true">
+        {title && <div className="card-title">{title}</div>}
+        <div style={{ padding: 'var(--space-6, 24px)' }}>{children}</div>
+      </div>
+    </div>,
+    document.body,
+  );
+}