feat: fire CHAT_MSG_* events to Lua addons for all chat types

Wire chat messages to the addon event system via AddonChatCallback.
Every chat message now fires the corresponding WoW event:

- CHAT_MSG_SAY, CHAT_MSG_YELL, CHAT_MSG_WHISPER
- CHAT_MSG_PARTY, CHAT_MSG_GUILD, CHAT_MSG_OFFICER
- CHAT_MSG_RAID, CHAT_MSG_RAID_WARNING, CHAT_MSG_BATTLEGROUND
- CHAT_MSG_SYSTEM, CHAT_MSG_CHANNEL, CHAT_MSG_EMOTE

Event handlers receive (eventName, message, senderName) arguments.
Addons can now filter, react to, or log chat messages in real-time.

src/game/game_handler.cpp

@@ -14521,6 +14521,7 @@ void GameHandler::addLocalChatMessage(const MessageChatData& msg) {
     if (chatHistory.size() > maxChatHistory) {
         chatHistory.pop_front();
     }
+    if (addonChatCallback_) addonChatCallback_(msg);
 }
 
 // ============================================================