CMSG_CAST_SPELL: WotLK adds a castFlags(u8) byte after spellId that TBC
2.4.3 does not have. Add TbcPacketParsers::buildCastSpell() to omit it,
preventing every spell cast from being rejected by TBC servers.
CMSG_USE_ITEM: WotLK adds a glyphIndex(u32) field between itemGuid and
castFlags that TBC 2.4.3 does not have. Add buildUseItem() override.
SMSG_MONSTER_MOVE: WotLK adds a uint8 unk byte after the packed GUID
(MOVEMENTFLAG2_UNK7 toggle) that TBC 2.4.3 does not have. Add
parseMonsterMove() override to fix NPC movement parsing — without this,
all NPC positions, durations, and waypoints parse from the wrong byte
offset, making all NPC movement appear broken on TBC servers.
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