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/showcase/mobile/src/screens/AnimationsScreen.tsx

@@ -0,0 +1,90 @@
+import React from 'react';
+import { View } from 'react-native';
+import { Text } from 'react-native-paper';
+import {
+  DTCard,
+  DTLabel,
+  DTStaggerContainer,
+  useDTTheme,
+  useScaleIn,
+  usePulse,
+} from '@dangerousthings/react-native';
+import type { DTVariant } from '@dangerousthings/react-native';
+import { ScreenContainer } from '../components/ScreenContainer';
+import { DemoSection } from '../components/DemoSection';
+import { CodeLabel } from '../components/CodeLabel';
+import { Animated } from 'react-native';
+
+export function AnimationsScreen() {
+  const theme = useDTTheme();
+  const scaleAnim = useScaleIn({ duration: 600 });
+  const pulseAnim = usePulse(true);
+
+  const modes: DTVariant[] = ['normal', 'emphasis', 'warning', 'success', 'other'];
+
+  return (
+    <ScreenContainer>
+      {/* Stagger Container */}
+      <DemoSection
+        title="DTStaggerContainer"
+        variant="normal"
+        description="Staggered scale-in entrance animation for child elements."
+      >
+        <DTStaggerContainer duration={330} interval={75}>
+          {modes.map((mode) => (
+            <DTCard key={mode} mode={mode} title={mode.toUpperCase()} style={{ marginBottom: 12 }}>
+              <Text variant="bodySmall" style={{ color: theme.colors.onSurface }}>
+                Staggered entrance with scale animation
+              </Text>
+            </DTCard>
+          ))}
+        </DTStaggerContainer>
+        <CodeLabel text="<DTStaggerContainer duration={330} interval={75}>" />
+      </DemoSection>
+
+      {/* Stagger with Labels */}
+      <DemoSection
+        title="Staggered Labels"
+        variant="emphasis"
+        description="Labels with staggered entrance animation."
+      >
+        <DTStaggerContainer duration={400} interval={100}>
+          {modes.map((mode) => (
+            <View key={mode} style={{ marginBottom: 8 }}>
+              <DTLabel primaryText={mode.toUpperCase()} mode={mode} />
+            </View>
+          ))}
+        </DTStaggerContainer>
+        <CodeLabel text="DTStaggerContainer > DTLabel — customizable timing" />
+      </DemoSection>
+
+      {/* Scale-In Hook */}
+      <DemoSection
+        title="useScaleIn"
+        variant="success"
+        description="Scale 0→1 entrance animation hook for individual elements."
+      >
+        <Animated.View style={{ transform: [{ scale: scaleAnim }] }}>
+          <DTCard mode="success" title="SCALE IN">
+            <Text variant="bodySmall" style={{ color: theme.colors.onSurface }}>
+              This card used useScaleIn(&#123; duration: 600 &#125;)
+            </Text>
+          </DTCard>
+        </Animated.View>
+        <CodeLabel text="const scale = useScaleIn({ duration: 600 })" />
+      </DemoSection>
+
+      {/* Pulse Hook */}
+      <DemoSection
+        title="usePulse"
+        variant="warning"
+        description="Looping opacity pulse animation for active/loading states."
+      >
+        <Animated.View style={{ opacity: pulseAnim }}>
+          <DTLabel primaryText="PULSING LABEL" mode="warning" />
+        </Animated.View>
+        <CodeLabel text="const opacity = usePulse(true)" />
+      </DemoSection>
+    </ScreenContainer>
+  );
+}