【框架设计】好友系统：好友上限与亲密度成长

---好友的添加：双向写入与上限
local FRIEND_CAP = 100

function Friend.add(actor, targetName)
    local player = class(actor)
    if not player then return false end
    local cnt = tonumber(getplayvar(actor, 2, "FriendCnt")) or 0
    if cnt >= FRIEND_CAP then
        sendmsg(actor, 1, "好友已达上限 100 人")
        return false
    end
    Friend.addTwoWay(actor, targetName)
    setplayvar(actor, "HUMAN", "FriendCnt", cnt + 1, 1)
    Friend.setIntimacy(actor, targetName, 10)
    return true
end

---亲密度的等级与权益
local INTIMACY_LEVELS = {
    { lv = 1, need = 0,   perk = "无" },
    { lv = 2, need = 100, perk = "好友传送" },
    { lv = 3, need = 500, perk = "组队经验 +5%" },
    { lv = 4, need = 1500, perk = "亲密度称号" },
}

function Friend.levelOf(actor, targetName)
    local player = class(actor)
    if not player then return 1 end
    local v = Friend.getIntimacy(actor, targetName)
    for i = #INTIMACY_LEVELS, 1, -1 do
        if v >= INTIMACY_LEVELS[i].need then
            return i
        end
    end
    return 1
end