Fix build-macos failure by forcing spdlog to std::format

[Copilot]

build-macos failed in Actions job 98239026558 while compiling spdlog due to a consteval format-string error in the bundled fmt path on macOS clang. This change adjusts CMake configuration so spdlog uses the standard library formatting path instead.

• Root cause

  • spdlog’s bundled fmt compile-time format-string path failed on macOS (fmt_helper.h consteval error).

• Build configuration change

  • In glinx-core/CMakeLists.txt, set SPDLOG_USE_STD_FORMAT before FetchContent_MakeAvailable(spdlog) so dependency configuration is applied at fetch/configure time.

• Scope

  • Single-file, surgical CMake change; no runtime API or behavior changes in Glinx codepaths.

FetchContent_Declare(
    spdlog
    GIT_REPOSITORY https://github.com/gabime/spdlog.git
    GIT_TAG v1.13.0
)
set(SPDLOG_USE_STD_FORMAT ON CACHE BOOL "Use std::format in spdlog" FORCE)
FetchContent_MakeAvailable(spdlog)