Migrate `C++` build system from direct `g++` to `CMake`

[deyna256]

Currently the project builds C++ code by directly passing all files to g++ using regex patterns and similar approaches. This is not maintainable. We should migrate to CMake for better dependency management, cross-platform support, and more robust build configuration.

[yegor256]

@literally-bug-creator I would not rush into this fix. The project is pretty small and a carefully crafted Makefile can do a better job than a pretty complicated CMake setup. It's my subjective option though, ready to hear counter arguments.