fix(shop-dealer-user): 修复手机号重复添加逻辑并更新用户ID

- 查询手机号是否已存在对应记录
- 如果存在则更新其userId为当前登录用户的userId
- 避免手机号重复添加，改为执行更新操作
- 保证手机号唯一性的同时允许用户信息变更
- 删除原有直接返回失败的逻辑，改为更新并返回成功状态

src/main/java/com/gxwebsoft/shop/controller/ShopDealerUserController.java

@@ -68,9 +68,15 @@ public class ShopDealerUserController extends BaseController {
         if (loginUser != null) {
          shopDealerUser.setUserId(loginUser.getUserId());
         }
-        // 排重
-        if (shopDealerUserService.count(new LambdaQueryWrapper<ShopDealerUser>().eq(ShopDealerUser::getMobile, shopDealerUser.getMobile())) > 0) {
-            return fail("添加失败，手机号码已存在！");
+        // 查询是否已存在该手机号的记录
+        ShopDealerUser existUser = shopDealerUserService.getOne(
+            new LambdaQueryWrapper<ShopDealerUser>().eq(ShopDealerUser::getMobile, shopDealerUser.getMobile())
+        );
+        if (existUser != null) {
+            // 手机号已存在，更新其 userId 为当前用户
+            existUser.setUserId(shopDealerUser.getUserId());
+            shopDealerUserService.updateById(existUser);
+            return success("更新成功", existUser);
         }
         if (shopDealerUserService.save(shopDealerUser)) {
             return success("添加成功", shopDealerUser);