【工具链】配置热重载：配表 diff 与增量生效

local HOT_FIELDS = { drop_rate = true, price = true, exp = true }
function HotReload.diff(oldTbl, newTbl)
    local changes = {}
    for k, v in pairs(newTbl) do
        if oldTbl[k] ~= v then
            changes[#changes + 1] = { key = k, from = oldTbl[k], to = v }
        end
    end
    for _, c in ipairs(changes) do
        if not HOT_FIELDS[c.key] then
            return false, "字段不可热更：" .. c.key
        end
    end
    return true, changes
end

function HotReload.apply(tblName, newTbl)
    local backup = configSnapshot[tblName]
    configSnapshot[tblName] = newTbl
    local ok, err = pcall(NotifyReload, tblName)
    if not ok then
        configSnapshot[tblName] = backup
        QF_NotifyGM("热重载回滚", tblName .. ":" .. tostring(err))
        return false
    end
    QF_LogReload(tblName, os.time())
    return true
end