Enhanced the C-key character screen with a 3-column layout featuring a 3D
character model preview (with drag-to-rotate), item icons loaded from BLP
textures via ItemDisplayInfo.dbc, and a stats panel showing base + equipment
bonuses. Fixed selection circle clipping under terrain by adding a Z offset,
and corrected faction hostility logic that was wrongly marking hostile mobs
as friendly.
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.
