fix: consume all SpellCastTargets bytes in WotLK SpellGoParser

Applied the same SpellCastTargets fix from SpellStartParser (dd64724)
to SpellGoParser: after parsing hit/miss target lists, now reads the
full target section (UNIT/UNIT_MINIPET/CORPSE/GAMEOBJECT packed GUID,
ITEM/TRADE_ITEM packed GUID, SOURCE/DEST PackedGuid+3floats, null-
terminated STRING). Also adds targetGuid field to SpellGoData so
callers can read the primary target. Prevents stream misalignment on
ground-targeted AoE spells (e.g. Blizzard, Rain of Fire).

include/game/world_packets.hpp

@@ -1875,6 +1875,7 @@ struct SpellGoData {
     std::vector<uint64_t>       hitTargets;
     uint8_t missCount = 0;
     std::vector<SpellGoMissEntry> missTargets;
+    uint64_t targetGuid = 0;  ///< Primary target GUID from SpellCastTargets (0 = none/AoE)
 
     bool isValid() const { return spellId != 0; }
 };