feat(shop): 添加商城列表页浮动购物车按钮

- 在 shop 页面右下角添加固定定位的绿色圆形购物车按钮
- 按钮右上角显示购物车商品数量角标，超过 99 显示为 99+
- 点击按钮跳转到购物车页面，非 tabBar 页面
- 使用 useCartContext 的 totalCount 实时更新商品数量显示
- 注释掉用户页面 “我的钱包” 入口，暂时隐藏该功能

src/pages/shop/index.tsx

@@ -36,7 +36,7 @@ const SORT_TABS: { key: SortKey; label: string }[] = [
 ]
 
 const ShopPage: React.FC = () => {
-  const { addItem } = useCartContext()
+  const { addItem, totalCount } = useCartContext()
   const [categoryList, setCategoryList] = useState<any[]>(PRESET_CATEGORIES)
   const [activeCategory, setActiveCategory] = useState(0)
 
@@ -343,6 +343,47 @@ const ShopPage: React.FC = () => {
         </ScrollView>
       </View>
       </View>
+
+      {/* 浮动购物车按钮 */}
+      <View
+        className='flex items-center justify-center'
+        style={{
+          position: 'fixed',
+          right: '16px',
+          bottom: '80px',
+          width: '48px',
+          height: '48px',
+          borderRadius: '50%',
+          backgroundColor: '#0e932e',
+          zIndex: 999,
+          boxShadow: '0 2px 8px rgba(0,0,0,0.15)',
+        }}
+        onClick={() => Taro.navigateTo({ url: '/pages/shop/cart' })}
+      >
+        <Text className='text-white text-xl'>🛒</Text>
+        {totalCount > 0 && (
+          <View
+            className='flex items-center justify-center'
+            style={{
+              position: 'absolute',
+              top: '-4px',
+              right: '-4px',
+              minWidth: '18px',
+              height: '18px',
+              borderRadius: '9px',
+              backgroundColor: '#ef4444',
+              borderWidth: '1.5px',
+              borderStyle: 'solid',
+              borderColor: '#ffffff',
+              paddingHorizontal: '4px',
+            }}
+          >
+            <Text className='text-white text-xs font-bold leading-none'>
+              {totalCount > 99 ? '99+' : totalCount}
+            </Text>
+          </View>
+        )}
+      </View>
     </View>
   )
 }