【数据存储】任务进度存储：断点续做与回退

---任务进度：按键值对持久化
function Quest.saveProgress(actor, questId, key, value)
    local player = class(actor)
    if not player then return false end
    local storeKey = "Q_" .. questId .. "_" .. key
    setplayvar(actor, "HUMAN", storeKey, value, 1)
    return true
end

---屠龙任务的进度读取
function Quest.progressOf(actor, questId, key)
    local storeKey = "Q_" .. questId .. "_" .. key
    return getplayvar(actor, 2, storeKey)
end

---屠龙刀任务第三环的进度示例
function Quest.dragonStep(actor)
    local step = Quest.progressOf(actor, "dragon", "step")
    return tonumber(step) or 1
end

---任务的重置：付费重做与奖励的防刷
function Quest.reset(actor, questId)
    local player = class(actor)
    if not player then return false end
    -- 已领奖的任务重做，奖励减半
    local claimed = Quest.progressOf(actor, questId, "claimed")
    if claimed == "1" then
        setplayvar(actor, "HUMAN", "Q_" .. questId .. "_halved", 1, 1)
        sendmsg(actor, 1, "重做任务的奖励将为 50%")
    end
    -- 只清进度，不动完成标记
    for _, key in ipairs(Quest.progressKeys(questId)) do
        Quest.saveProgress(actor, questId, key, "")
    end
    sendmsg(actor, 1, "任务已重置，可重新开始")
    return true
end