Render an animated M2 character model in the creation screen using a
dedicated CharacterRenderer with an offscreen FBO. Preview updates on
race/gender/appearance changes, supports mouse-drag rotation, and
composites skin, face, hair scalp, and underwear textures from
CharSections.dbc. Extracts getPlayerModelPath() to a shared free
function in game/character.
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.
