🐛 fix(wechat-coupons): 修复筛选条件默认值问题

- 将stockId和status的默认值从空字符串改为"all"
- 调整筛选逻辑，仅当值不为"all"时才添加筛选条件
- 更新下拉选择框的"全部"选项值为"all"以保持一致

src/client/admin-shadcn/pages/WechatCoupons.tsx

@@ -26,8 +26,8 @@ export const WechatCouponsPage = () => {
     page: 1,
     limit: 10,
     search: '',
-    stockId: '',
-    status: '',
+    stockId: 'all',
+    status: 'all',
   })
 
   // 获取代金券批次列表
@@ -47,8 +47,8 @@ export const WechatCouponsPage = () => {
     queryKey: ['wechat-coupons', searchParams],
     queryFn: async () => {
       const filters: any = {}
-      if (searchParams.stockId) filters.stockId = searchParams.stockId
-      if (searchParams.status) filters.couponStatus = searchParams.status
+      if (searchParams.stockId && searchParams.stockId !== 'all') filters.stockId = searchParams.stockId
+      if (searchParams.status && searchParams.status !== 'all') filters.couponStatus = searchParams.status
 
       const res = await wechatCouponClient.$get({
         query: {
@@ -111,7 +111,7 @@ export const WechatCouponsPage = () => {
                 <SelectValue placeholder="选择批次" />
               </SelectTrigger>
               <SelectContent>
-                <SelectItem value="">全部批次</SelectItem>
+                <SelectItem value="all">全部批次</SelectItem>
                 {stockData?.data.map((stock) => (
                   <SelectItem key={stock.id} value={stock.stockId}>
                     {stock.stockName}
@@ -127,7 +127,7 @@ export const WechatCouponsPage = () => {
                 <SelectValue placeholder="全部状态" />
               </SelectTrigger>
               <SelectContent>
-                <SelectItem value="">全部状态</SelectItem>
+                <SelectItem value="all">全部状态</SelectItem>
                 <SelectItem value="SENDED">已发放</SelectItem>
                 <SelectItem value="USED">已使用</SelectItem>
                 <SelectItem value="EXPIRED">已过期</SelectItem>