【网络通信】关键请求回执补发：SL:SendNetMsg的序号与超时重试

local seq, pending = 0, {}
local function sendKey(cmd, body)
    seq = seq + 1
    pending[seq] = { cmd = cmd, body = body, retry = 0 }
    SL:SendNetMsg(cmd, { sq = seq, body = body })
    SL:Schedule(function()
        local p = pending[seq]
        if p and p.retry < 3 then
            p.retry = p.retry + 1
            SL:SendNetMsg(cmd, { sq = seq, body = body })
        end
    end, 3)
    return seq
end
sendKey(6201, { item = "回城卷", num = 1 })

SL:RegisterLuaNetMsg(6202, function(data)
    local sq = tonumber(data.sq) or 0
    if pending[sq] then
        pending[sq] = nil
        SL:ShowSystemTips("购买成功，回城卷已入包")
    end
end)