Move envSizeMBOrDefault and envSizeOrDefault from 4 separate rendering
modules (character_renderer, m2_renderer, terrain_renderer, wmo_renderer)
into shared vk_utils.hpp header as inline functions. Use the most robust
version which includes overflow checking for MB-to-bytes conversion. This
eliminates 7 identical local function definitions and improves consistency
across all rendering modules.
- vk_utils.hpp: mark unused 'msg' parameter with [[maybe_unused]]
- world_packets.cpp: write exactMatch field to auction list packet
(was accepted as parameter but never serialized)
- game_screen.cpp: remove unused bagIcons array and unused info variable
- talent_screen.cpp: remove unused nextRank and pMin variables