【后端接口】激活码兑换：CDK 礼包的核销链

---CDK 兑换：校验、核销、发货三步
function Cdk.redeem(actor, code)
    local player = class(actor)
    if not player then return false end
    if #code ~= 16 then
        sendmsg(actor, 1, "激活码格式不正确")
        return false
    end
    local record = Cdk.store[code]
    if not record then
        sendmsg(actor, 1, "激活码不存在")
        return false
    end
    if record.used then
        sendmsg(actor, 1, "该激活码已被使用")
        return false
    end
    -- 核销与发货同一流程
    record.used = true
    record.usedBy = actor:GetUserId()
    record.usedAt = os.time()
    giveitem(actor, record.item, record.count)
    sendmsg(actor, 1, "兑换成功：" .. record.item .. " x" .. record.count)
    return true
end

---批量生成：媒体投放的码池
function Cdk.generate(batchId, count, itemId, itemCount)
    local out = {}
    for i = 1, count do
        local code = Cdk.randomCode()
        Cdk.store[code] = {
            batch = batchId,
            item = itemId, count = itemCount,
            expireAt = os.time() + 30 * 86400,
        }
        out[i] = code
    end
    Ops.log("生成批次 " .. batchId .. " 共 " .. count .. " 个激活码")
    return out
end