feat: add CartButton component for consistent cart access across views

- Introduced a new CartButton component to encapsulate cart summary functionality, improving code reusability and maintainability.
- Updated MarketPage.vue and StallView.vue to utilize the CartButton component, enhancing user navigation to the cart.
- Removed redundant cart summary code from both views, streamlining the component structure.

These changes provide a unified and consistent user experience for accessing the cart across different market views.

src/modules/market/components/CartButton.vue

@@ -0,0 +1,23 @@
+<template>
+  <!-- Cart Summary Button -->
+  <div v-if="marketStore.totalCartItems > 0" class="fixed bottom-4 right-4 z-50">
+    <Button @click="viewCart" class="shadow-lg">
+      <ShoppingCart class="w-5 h-5 mr-2" />
+      Cart ({{ marketStore.totalCartItems }})
+    </Button>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { useRouter } from 'vue-router'
+import { useMarketStore } from '@/modules/market/stores/market'
+import { Button } from '@/components/ui/button'
+import { ShoppingCart } from 'lucide-vue-next'
+
+const router = useRouter()
+const marketStore = useMarketStore()
+
+const viewCart = () => {
+  router.push('/cart')
+}
+</script>