Add Linux support and CI

[kwsp]

1. Github Action: added "Build-Linux" job.
2. C++ std lib compliance: Added #include <memory> to resolve std::unique_ptr compiler error. AppleClang and MSVC includes <memory> automatically while libc++ on Linux does not.
3. CMake find_package: linux file system is case-sensitive, so benchmark must be lower case.
4. Manually tested with Clang on linux and Python build with uv pip install .