【前端接口】商店限购倒计时：Text_COUNTDOWN与每日刷新联动

local function renderShopItem(widget, left, refreshTs)
    if left > 0 then
        GUI:setText(widget, "购买（剩" .. left .. "个）")
        GUI:setVisible(countdownTxt, false)
    else
        local remain = refreshTs - os.time()
        GUI:setText(widget, "已售罄")
        GUI:setVisible(countdownTxt, true)
        GUI:Text_COUNTDOWN(countdownTxt, remain, function()
            GUI:setText(widget, "购买（剩3个）")
            SL:ShowSystemTips("今日限量已刷新")
        end, 1)
    end
end

GUI:addOnClickEvent(buyBtn, function()
    SL:SendNetMsg(6601, { goods = 3 })
end)
SL:RegisterLuaNetMsg(6602, function(data)
    if data.ok == 1 then
        shopLeft = shopLeft - 1
        renderShopItem(buyBtn, shopLeft, data.refreshTs)
    else
        SL:ShowSystemTips("手慢了，今日已售罄")
    end
end)