fix(deps): upgrade tailwind-merge to v3 and declare lucide-react in storefront

- apps/admin: tailwind-merge ^2.6.1 → ^3.4.0 so root resolves to v3.x,
  satisfying @heroui/styles/node_modules/tailwind-variants peer dep (>=3.0.0)
- apps/storefront: add lucide-react ^0.400.0 as explicit dep (used in
  SearchEmptyState and SearchResultsPanel but was previously undeclared)

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

apps/storefront/package.json

@@ -18,6 +18,7 @@
     "@repo/utils": "*",
     "@stripe/react-stripe-js": "^5.6.0",
     "@stripe/stripe-js": "^8.8.0",
-    "framer-motion": "^11.0.0"
+    "framer-motion": "^11.0.0",
+    "lucide-react": "^0.400.0"
   }
 }