【后端接口】摆摊系统：离线挂单与自动结算

---上架：扣摊位费，物品转托管
function Stall.list(actor, makeIndex, price)
    local n = tonumber(getplayvar(actor, 2, "StallCount")) or 0
    if n >= 20 then
        sendmsg(actor, 1, "摊位最多挂 20 件")
        return false
    end
    if not checkitemw(actor, "金币", 20000) then
        sendmsg(actor, 1, "摊位费不足，需 2 万金币")
        return false
    end
    takeitem(actor, "金币", 20000, 0, "摊位费")
    setplayvar(actor, "HUMAN", "Stall_" .. n, makeIndex .. ":" .. price, 1)
    setplayvar(actor, "HUMAN", "StallCount", n + 1, 1)
    sendmsg(actor, 1, "上架成功，摊位费 2 万金币已收")
    return true
end

---自动结算：每 30 分钟扫一次成交
setontimerex(74, 1800)
function Stall.settle(actor)
    local n = tonumber(getplayvar(actor, 2, "StallCount")) or 0
    local earned = 0
    for i = 0, n - 1 do
        local slot = "Stall_" .. i
        local v = getplayvar(actor, 2, slot)
        if v and Stall.sold(v) then
            local price = tonumber(v:match(":(%d+)$")) or 0
            earned = earned + math.floor(price * 0.95)
            setplayvar(actor, 2, slot, "", 1)
        end
    end
    if earned > 0 then
        sendmail(actor:GetUserId(), 8006, "摆摊结算",
            "您的摊位售出商品，扣除 5% 手续费",
            "金币|" .. earned)
    end
end