Add Linux Compatibility and Build Scripts

[el-dockerr]

This pull request introduces comprehensive cross-platform (Windows and Linux) build and runtime support for the GhostMem project. It adds CMake-based and direct build scripts, updates the documentation for cross-platform usage, and implements Linux-specific memory management and page fault handling. The changes modernize the build process, clarify platform requirements, and enable transparent memory compression on both Windows and Linux.

Cross-platform build and CI improvements:

• Added a cross-platform CMake build system in CMakeLists.txt, supporting static/shared libraries and test builds for both Windows and Linux, with appropriate platform-specific compiler and linker flags.
• Introduced GitHub Actions CI workflow (.github/workflows/build-and-test.yml) to automatically build, test, and perform static analysis on Windows and Linux for pull requests and pushes.
• Added direct build scripts for quick compilation without CMake: build-simple.bat (Windows) and build-simple.sh (Linux); also added recommended build scripts using CMake: build.bat (Windows) and build.sh (Linux). [1] [2] [3] [4]

Linux support and platform abstraction:

• Implemented Linux-specific memory reservation (using mmap), page protection/deprotection (using mprotect), and SIGSEGV-based page fault handling in GhostMemoryManager.cpp, enabling transparent memory compression on Linux. [1] [2] [3] [4]
• Updated allocator headers to use #pragma once and ensure proper includes for cross-platform compatibility.

Documentation and usability improvements:

• Significantly revised the README.md to document Linux support, build requirements, usage instructions, and output artifacts for both platforms. Added sections for quick/direct and CMake-based builds, and clarified the roadmap and limitations. [1] [2] [3]
• Added copyright and descriptive comments to GhostMemoryManager.cpp.

References:
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]