refactor: world packets as structs

WorldPackets now holds what a client sends a world server, one struct per
packet with Serialize/Deserialize: Validation, CharacterListRequest,
CharacterCreateRequest, CharacterLoginRequest, GameMessage,
CharacterDeleteRequest, CharacterRenameRequest, LevelLoadComplete,
PositionUpdate, MailPacket, RoutePacket, StringCheck, GeneralChatMessage,
HandleFunness, UIHelpTop5. WorldServer's switch became a dispatch map of
handlers (each overrides Handle in WorldServer.cpp, logic unchanged:
dashboard hooks, LoadPlayer, chat logging, migration checks, message
inspector capture all still run); a packet that does not deserialize is
logged and dropped. UserManager's create/delete/rename take the structs.

The answers are ClientPackets (the CLIENT service): LoadStaticZone,
CharacterListResponse, CharacterCreateResponse, CharacterRenameResponse,
DeleteCharacterResponse, TransferToWorld, ServerStates, CreateCharacter,
ChatModerationString, MakeGMResponse, HTTPMonitorInfoResponse and
DebugOutput, built at the call sites (world server, UserManager, slash
commands, dashboard actions, components, migration). The world -> chat
forward of a routed packet is ChatPackets::RoutedFromClient. All
WorldPackets::Send* functions, HTTPMonitorInfo and the ClientPackets parse
functions are gone. The architecture doc now states the file rule: a
packet lives in the file of the ServiceType in its header.

No wire change. Verified against frozen verbatim copies of the old code
(tests/dGameTests/dNetTests/Legacy/WorldPacketsLegacy.h): every response
is sent through the old function and the struct over grids of inputs
(all enum values, strings of every length class, IDs, >64 moderation
segments, big XML) and must match byte for byte; every request is read
by the old code and the struct and must give the same values; plus
golden bytes, round trips, truncation checks and a field width mutation
that made the tests fail. Only differences: malformed requests are
dropped instead of handled with partial values, and LevelLoadComplete now
reads the zone ID the client sends after it (lu_packets and captures show
the 1.10.64 client always sends it; DLU ignored it).

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

docs/PacketArchitecture.md

@@ -159,9 +159,14 @@ Every non-game-message packet is an `LUBitStream` subclass. The base owns the fu
 - Each service has one dispatch function with a `std::map<MessageType::X, factory>`, exactly like
   `Mail::HandleMail`: read the id, create, set context, `Deserialize` (log and drop on failure), `Handle`. Each
   server's `HandlePacket` only routes by `ServiceType`.
-- Structs live in their service's namespace and file: `AuthPackets`, `ChatPackets`, `ClientPackets`,
-  `CommonPackets` (new, for `ServiceType::COMMON`), `MasterPackets`, `WorldPackets` in `dNet/`; Mail stays in
-  `dGame/dUtilities/Mail.*`. Handlers that need game or server state stay in the server that owns that state
+- **One file pair per `ServiceType`; a packet goes in the file of the `ServiceType` written in its header**, in
+  that namespace: `CommonPackets` (COMMON), `AuthPackets` (AUTH), `ChatPackets` (CHAT), `WorldPackets` (WORLD:
+  what a client sends to a world server), `ClientPackets` (CLIENT: what any server sends to the client),
+  `MasterPackets` (MASTER), all in `dNet/`. So the auth server's login response is in `ClientPackets`, and a
+  world server's message to chat is in `ChatPackets`. Anything used by several services (for example `Stamps`,
+  which rides in auth, master and client packets, or generic helpers) gets its own small file named for what it
+  is (`dNet/Stamps.h`), not one service's file. A packet found in the wrong file is moved (a pure move, same
+  bytes). Mail stays in `dGame/dUtilities/Mail.*`. Handlers that need game or server state stay in the server that owns that state
   (`dChatServer`, `dMasterServer`, `dWorldServer`, `dAuthServer`) and are attached to the struct by overriding
   `Handle` in that server's translation unit.
 - Fixed-width strings use `LUString`/`LUWString` with the width spelled out (`LUWString password(41)`).