Fix Classic/Turtle spell casting, cast fail parsing, and empty chat

Three Classic packet format fixes:

1. CMSG_CAST_SPELL: target flags are uint32 (not uint16). The wrong
   size caused the server to misparse the packet as an item enchant
   operation, returning "item already enchanted".

2. SMSG_CAST_FAILED: Classic has no castCount byte prefix (added in
   TBC). Added parseCastFailed override to ClassicPacketParsers.
   Without this, the parser read the wrong bytes and produced
   "Spell cast failed (error 0)" for every failure.

3. SMSG_MESSAGECHAT: Removed spurious receiverGuid read for SAY/YELL
   types. Classic chat format has no second GUID before the message
   body — the extra 8-byte read consumed messageLen + message data,
   producing empty chat messages.

include/game/packet_parsers.hpp

@@ -95,6 +95,11 @@ public:
         return InitialSpellsParser::parse(packet, data);
     }
 
+    /** Parse SMSG_CAST_FAILED */
+    virtual bool parseCastFailed(network::Packet& packet, CastFailedData& data) {
+        return CastFailedParser::parse(packet, data);
+    }
+
     /** Parse SMSG_AURA_UPDATE / SMSG_AURA_UPDATE_ALL */
     virtual bool parseAuraUpdate(network::Packet& packet, AuraUpdateData& data, bool isAll = false) {
         return AuraUpdateParser::parse(packet, data, isAll);
@@ -207,6 +212,7 @@ public:
                                          const MovementInfo& info,
                                          uint64_t playerGuid = 0) override;
     network::Packet buildCastSpell(uint32_t spellId, uint64_t targetGuid, uint8_t castCount) override;
+    bool parseCastFailed(network::Packet& packet, CastFailedData& data) override;
     bool parseMessageChat(network::Packet& packet, MessageChatData& data) override;
     bool parseGuildRoster(network::Packet& packet, GuildRosterData& data) override;
     bool parseGuildQueryResponse(network::Packet& packet, GuildQueryResponseData& data) override;

src/game/game_handler.cpp

@@ -6570,7 +6570,9 @@ void GameHandler::handleInitialSpells(network::Packet& packet) {
 
 void GameHandler::handleCastFailed(network::Packet& packet) {
     CastFailedData data;
-    if (!CastFailedParser::parse(packet, data)) return;
+    bool ok = packetParsers_ ? packetParsers_->parseCastFailed(packet, data)
+                             : CastFailedParser::parse(packet, data);
+    if (!ok) return;
 
     casting = false;
     currentCastSpellId = 0;

src/game/packet_parsers_classic.cpp

@@ -267,9 +267,9 @@ network::Packet ClassicPacketParsers::buildCastSpell(uint32_t spellId, uint64_t
 
     packet.writeUInt32(spellId);
 
-    // SpellCastTargets — vanilla uses uint16 target mask (not uint32 like WotLK)
+    // SpellCastTargets — vanilla/CMaNGOS uses uint32 target mask (same as WotLK)
     if (targetGuid != 0) {
-        packet.writeUInt16(0x02); // TARGET_FLAG_UNIT
+        packet.writeUInt32(0x02); // TARGET_FLAG_UNIT
 
         // Write packed GUID
         uint8_t mask = 0;
@@ -289,12 +289,24 @@ network::Packet ClassicPacketParsers::buildCastSpell(uint32_t spellId, uint64_t
             packet.writeUInt8(bytes[i]);
         }
     } else {
-        packet.writeUInt16(0x00); // TARGET_FLAG_SELF
+        packet.writeUInt32(0x00); // TARGET_FLAG_SELF
     }
 
     return packet;
 }
 
+// ============================================================================
+// Classic SMSG_CAST_FAILED: no castCount byte (added in TBC/WotLK)
+// Format: spellId(u32) + result(u8)
+// ============================================================================
+bool ClassicPacketParsers::parseCastFailed(network::Packet& packet, CastFailedData& data) {
+    data.castCount = 0;
+    data.spellId = packet.readUInt32();
+    data.result = packet.readUInt8();
+    LOG_INFO("[Classic] Cast failed: spell=", data.spellId, " result=", (int)data.result);
+    return true;
+}
+
 // ============================================================================
 // Classic 1.12.1 parseCharEnum
 // Differences from TBC:
@@ -437,16 +449,9 @@ bool ClassicPacketParsers::parseMessageChat(network::Packet& packet, MessageChat
         }
     }
 
-    // Vanilla/Classic: target GUID follows type-specific header for non-monster types
+    // Classic SAY/YELL/PARTY/GUILD/etc: NO second GUID before message.
-    // (Monster types already read target/receiver in their switch case)
+    // Only WHISPER_INFORM has a receiver GUID (same as sender for echo).
-    if (data.type != ChatType::MONSTER_SAY &&
+    // Do NOT read an extra uint64 here — it would consume messageLen + message bytes.
-        data.type != ChatType::MONSTER_YELL &&
-        data.type != ChatType::MONSTER_EMOTE &&
-        data.type != ChatType::CHANNEL) {
-        if (packet.getReadPos() + 12 <= packet.getSize()) { // 8 (guid) + 4 (msgLen) minimum
-            data.receiverGuid = packet.readUInt64();
-        }
-    }
 
     // Read message length
     uint32_t messageLen = packet.readUInt32();