Add Tier 6 commands: party/raid management

- Uninvite/kick: /uninvite, /kick <player name> to remove player from party/raid
- Leave party: /leave, /leaveparty to leave current group
- Main tank: /maintank, /mt to set target as main tank (uses raid marker index 0)
- Main assist: /mainassist, /ma to set target as main assist (uses raid marker index 1)
- Clear markers: /clearmaintank, /clearmainassist to remove designations
- Raid info: /raidinfo to display raid lockouts and saved instances

Added opcodes:
- CMSG_REQUEST_RAID_INFO (0x2CD) for requesting raid lockout info
- SMSG_RAID_INSTANCE_INFO (0x2CC) for receiving raid info response

New packet builders:
- GroupUninvitePacket for removing players from group
- GroupDisbandPacket for leaving party (with logging)
- RaidTargetUpdatePacket for setting raid markers (main tank/assist)
- RequestRaidInfoPacket for querying raid lockouts

All commands include proper validation and user feedback.

include/game/game_handler.hpp

@@ -261,6 +261,15 @@ public:
     std::string getLastWhisperSender() const { return lastWhisperSender_; }
     void setLastWhisperSender(const std::string& name) { lastWhisperSender_ = name; }
 
+    // Party/Raid management
+    void uninvitePlayer(const std::string& playerName);
+    void leaveParty();
+    void setMainTank(uint64_t targetGuid);
+    void setMainAssist(uint64_t targetGuid);
+    void clearMainTank();
+    void clearMainAssist();
+    void requestRaidInfo();
+
     // ---- Phase 1: Name queries ----
     void queryPlayerName(uint64_t guid);
     void queryCreatureInfo(uint32_t entry, uint64_t guid);