refactor(mhfpacket): rename 15 Unk fields with identified meanings

Replace unknown field names with descriptive names based on handler
logic analysis, switch dispatch patterns, DB query context, and
inline comments:

- ObjectHandleID, IsQuest, ItemIDCount, MaxCount, TokenLength,
  FormatVersion, LogoutType (high confidence from comments/constants)
- QueryType, DataType, MissionIndex, CheckOnly, RequestType,
  ExchangeType, TournamentID (confirmed by handler switch/if usage)

Also fix MsgSysLogout.Build calling ReadUint8 instead of WriteUint8.

network/mhfpacket/msg_mhf_get_tenrouirai.go

@@ -11,11 +11,11 @@ import (
 // MsgMhfGetTenrouirai represents the MSG_MHF_GET_TENROUIRAI
 type MsgMhfGetTenrouirai struct {
 	AckHandle uint32
-	Unk0      uint8
-	Unk1      uint8
-	GuildID   uint32
-	Unk3      uint8
-	Unk4      uint8
+	Unk0         uint8
+	DataType     uint8
+	GuildID      uint32
+	MissionIndex uint8
+	Unk4         uint8
 }
 
 // Opcode returns the ID associated with this packet type.
@@ -27,9 +27,9 @@ func (m *MsgMhfGetTenrouirai) Opcode() network.PacketID {
 func (m *MsgMhfGetTenrouirai) Parse(bf *byteframe.ByteFrame, ctx *clientctx.ClientContext) error {
 	m.AckHandle = bf.ReadUint32()
 	m.Unk0 = bf.ReadUint8()
-	m.Unk1 = bf.ReadUint8()
+	m.DataType = bf.ReadUint8()
 	m.GuildID = bf.ReadUint32()
-	m.Unk3 = bf.ReadUint8()
+	m.MissionIndex = bf.ReadUint8()
 	m.Unk4 = bf.ReadUint8()
 	return nil
 }