feat(platform): add Wii cross-compilation environment master
Add devkitPPC/libogc toolchain, platform abstraction layer, and stub implementations for transport, crypto, and TLS so the SDK can cross-compile for Nintendo Wii with WOLFRAM_BUILD_WII=ON. Client-only build: excludes server modules, OAuth flows, and desktop-specific dependencies (libcurl, OpenSSL, pthreads). - CMake toolchain (.devdeps/wii.cmake) for powerpc-eabi-gcc - Platform abstraction (mutex, time, init) with POSIX and Wii impls - XRPC/WebSocket transport stubs (lwIP + mbedTLS TODO) - Crypto stubs with pure-C SHA-256 and base64url - OpenSSL compat shim for existing source files Also fixes pre-existing devkitPPC build issues: - syntax.c: include sys/types.h before regex.h (off_t) - agent.c: use non-auth call variant for updateHandle