refactor: chat packets as structs

Every packet of the chat service is now an LUBitStream struct in dNet/ChatPackets.h
(docs/PacketArchitecture.md, PR 13), and nothing in the chat server or the chat side of
the world server reads or writes a packet by hand any more.

- World <-> chat: LoginSessionNotify, UnexpectedDisconnect, GMLevelUpdate, GMMute,
  Announcement (GM announce), CreateTeam, TeamUpdate (TEAM_GET_STATUS to worlds),
  AchievementNotify, ShowAllRequest, FindPlayerRequest.
- Client -> world -> chat (friends, ignore list, teams, general and private chat):
  GetFriendsList, AddFriendRequest, AddFriendResponse, RemoveFriend, GetIgnoreList,
  AddIgnore, RemoveIgnore, GeneralChatMessage, PrivateChatMessage, TeamInvite,
  TeamInviteResponse, TeamLeave, TeamKick, TeamSetLeader, TeamSetLoot, TeamGetStatus.
  The 77 bytes the handlers skipped are named fields now (the sender block the client
  fills in); the 4 unused bytes after the player ID are kept as `unknown`.
- What the client receives. Chat service (ChatPackets::Client): GeneralChatMessage
  (replaces SendChatMessage; SendSystemMessage stays as a helper built on it),
  PrivateChatMessage. Client service (ClientPackets, as structs go in the file of the
  ServiceType in their header): SendCannedText (replaces SendMessageFail), GetFriendsListResponse, AddFriendRequest,
  AddFriendResponse, RemoveFriendResponse, UpdateFriendNotify, WhoResponse,
  ShowAllResponse, Get/Add/RemoveIgnoreResponse, TeamInvite, TeamInviteInitialResponse,
  and the team game messages chat writes (TeamInviteConfirm, TeamGetStatusResponse,
  TeamSetLeader, TeamAddPlayer, TeamRemovePlayer, TeamSetOffWorldFlag) as TeamGameMsg
  structs, since chat doesn't link dGame's NetGameMsg.
- WORLD_ROUTE_PACKET is ChatPackets::WorldRoutePacket (its own file, dNet/WorldRoutePacket.h,
  since it carries packets of other services): the target and the inner packet.
  ChatPacketHandler::SendRouted replaces the per-function route headers and
  SendRoutedMsg.

Dispatch: dNet/PacketDispatcher.h is a dispatch map from packet ID to (struct, handler
function); packets that fail to Deserialize are logged and dropped. The chat server's
switch and the world's HandlePacketChat switch are now maps. The handlers take the
structs; their logic is unchanged. World code sends to chat with ChatServerLink::Send
(dGame) instead of writing to Game::chatServer by hand. eChatChannel,
eChatMessageResponseCode and eAddIgnoreResponse moved to dCommon/dEnums so the structs
can use them.

Verified: tests/dGameTests/dNetTests/Legacy/ChatPacketsLegacy.h is a verbatim copy of
the old senders and readers; ChatPacketsTests (25 tests) sends a grid of inputs through
both and requires identical bits, bytes and destination, checks the old readers read
what the structs write, round trips every struct, checks truncated packets are refused,
and has hand written golden packets for general chat, canned text, GM mute and a routed
team game message. Breaking one field width (UpdateFriendNotify) and the TeamAddPlayer
zone flag made the tests fail. No wire bytes changed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dChatServer/ChatPacketHandler.h

@@ -2,60 +2,31 @@
 #include "dCommonVars.h"
 #include "dNetCommon.h"
 #include "BitStream.h"
+#include "ChatPackets.h"
+#include "ClientPackets.h"
+#include "WorldRoutePacket.h"
+#include "eChatChannel.h"
+#include "eChatMessageResponseCode.h"
 
 struct PlayerData;
+struct LUBitStream;
 
 enum class eAddFriendResponseType : uint8_t;
 
-enum class eChatChannel : uint8_t {
-	SYSTEMNOTIFY = 0,
-	SYSTEMWARNING,
-	SYSTEMERROR,
-	BROADCAST,
-	LOCAL,
-	LOCALNOANIM,
-	EMOTE,
-	PRIVATE_CHAT,
-	TEAM,
-	TEAMLOCAL,
-	GUILD,
-	GUILDNOTIFY,
-	PROPERTY,
-	ADMIN,
-	COMBATDAMAGE,
-	COMBATHEALING,
-	COMBATLOOT,
-	COMBATEXP,
-	COMBATDEATH,
-	GENERAL,
-	TRADE,
-	LFG,
-	USER
-};
-
-
-enum class eChatMessageResponseCode : uint8_t {
-	SENT = 0,
-	NOTONLINE,
-	GENERALERROR,
-	RECEIVEDNEWWHISPER,
-	NOTFRIENDS,
-	SENDERFREETRIAL,
-	RECEIVERFREETRIAL,
-};
-
 namespace ChatPacketHandler {
-	void HandleFriendlistRequest(Packet* packet);
-	void HandleFriendRequest(Packet* packet);
-	void HandleFriendResponse(Packet* packet);
-	void HandleRemoveFriend(Packet* packet);
-	void HandleGMLevelUpdate(Packet* packet);
-	void HandleWho(Packet* packet);
-	void HandleShowAll(Packet* packet);
-	void HandleChatMessage(Packet* packet);
-	void HandlePrivateChatMessage(Packet* packet);
+	// Sends msg to the world server `world`, which passes it on to the client of `target`
+	void SendRouted(const LWOOBJID target, const SystemAddress& world, const LUBitStream& msg, const bool broadcast = false);
 
-	void OnAchievementNotify(RakNet::BitStream& bitstream, const SystemAddress& sysAddr);
+	void HandleFriendlistRequest(const ChatPackets::GetFriendsList& request, const SystemAddress& sysAddr);
+	void HandleFriendRequest(const ChatPackets::AddFriendRequest& request, const SystemAddress& sysAddr);
+	void HandleFriendResponse(const ChatPackets::AddFriendResponse& response, const SystemAddress& sysAddr);
+	void HandleRemoveFriend(const ChatPackets::RemoveFriend& request, const SystemAddress& sysAddr);
+	void HandleGMLevelUpdate(const ChatPackets::GMLevelUpdate& update, const SystemAddress& sysAddr);
+	void HandleWho(const ChatPackets::FindPlayerRequest& request, const SystemAddress& sysAddr);
+	void HandleShowAll(const ChatPackets::ShowAllRequest& request, const SystemAddress& sysAddr);
+	void HandleChatMessage(const ChatPackets::GeneralChatMessage& chatMessage, const SystemAddress& sysAddr);
+	void HandlePrivateChatMessage(const ChatPackets::PrivateChatMessage& chatMessage, const SystemAddress& sysAddr);
+	void OnAchievementNotify(ChatPackets::AchievementNotify& notify, const SystemAddress& sysAddr);
 
 	//FriendData is the player we're SENDING this stuff to. Player is the friend that changed state.
 	void SendFriendUpdate(const PlayerData& friendData, const PlayerData& playerData, uint8_t notifyType, uint8_t isBestFriend);