Add Badge, Chip, and IconButton components with token layers

- Badge: 11 solid-colour variants (navy, info, success, error, warning + light variants, neutral, white) with icon slots
- Chip: bordered interactive element with selected, dismissible, and disabled states
- IconButton: circle/square shapes, 3 variants × 3 intents × 3 sizes, uses lucide-react icons
- Add badge and chip domain token layers to tokens.css
- Configure extendTailwindMerge in cn() to recognise custom font-size utilities (text-small, text-body, etc.)

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

package.json

@@ -41,6 +41,7 @@
     "eslint-plugin-react-refresh": "^0.5.2",
     "eslint-plugin-storybook": "^10.4.0",
     "globals": "^17.6.0",
+    "lucide-react": "^1.16.0",
     "playwright": "^1.60.0",
     "prettier": "^3.8.3",
     "prettier-plugin-tailwindcss": "^0.8.0",