Implements a full character creation UI integrated into the existing flow.
In single-player mode, auth screen now goes to character creation before
entering the world. In online mode, a "Create Character" button on the
character selection screen sends CMSG_CHAR_CREATE to the server. Includes
WoW 3.3.5a race/class combo validation and appearance range limits.
Teleporter panel (T key) lets the player teleport between Goldshire,
Stormwind Gate, Ironforge, and Westfall in single-player mode. Adds
serverToCanonical/canonicalToServer conversion at the network packet
boundary so positions are compatible with TrinityCore/MaNGOS/AzerothCore
emulator servers.
Centralizes all coordinate conversions in core/coordinates.hpp with
proper canonical WoW coords (+X=North, +Y=West, +Z=Up). Fixes critical
tile calculation bug that was loading wrong surrounding tiles during
terrain streaming, and fixes position sync sending ADT-raw format
instead of canonical coordinates to the server.
