Three critical bugs fixed:
- LOGON_CHALLENGE request: set protocol byte to 0x03 (was 0x00) and
reverse FourCC strings (game/platform/os/locale) to match real client
- Response parsers: remove double-read of opcode byte that shifted all
field reads by one, preventing successful auth with real servers
- LOGON_PROOF response sizes: success=32 bytes, failure=4 bytes to match
TrinityCore/AzerothCore format
Also adds missing auth result codes (0x13-0x20, 0xFF) including
IGR_WITHOUT_BNET (0x17) which Warmane was returning.
Replace POSIX-specific socket and process APIs with portable
abstractions so the project builds on both Windows and Linux.
- Add include/network/net_platform.hpp: Winsock2/POSIX socket
abstraction (socket types, non-blocking, error handling,
WSAStartup lifecycle)
- Add include/platform/process.hpp: CreateProcess/fork+exec
abstraction for spawning ffplay subprocesses
- Update network module (tcp_socket, world_socket) to use
portable socket helpers instead of raw POSIX calls
- Update audio module (music_manager, footstep_manager,
activity_sound_manager) to use portable process helpers
instead of fork/exec/kill/waitpid
- Replace hardcoded /tmp/ paths with std::filesystem::temp_directory_path()
- Link ws2_32 and SDL2main on Windows in CMakeLists.txt
