Streamline cross-platform kata setup

[megabyde]

Summary

• find an installed GoogleTest or download and verify GoogleTest 1.17 automatically
• use make test locally and throughout the Ubuntu, macOS, and Windows CI matrix
• retain direct CMake/CTest commands for environments where Make is unavailable
• make bare make print colored help without creating build artifacts
• document concrete compiler choices, clone/setup steps, and observable completion criteria
• add CODEOWNERS, weekly GitHub Actions Dependabot updates, current action versions, and badges
• remove the redundant VS Code test-task build dependency

Verification

• make
• CCACHE_DIR=/tmp/bootstrap-cpp-kata-ccache make test
• make format-check
• cmake-lint CMakeLists.txt cmake/FetchGTest.cmake
• markdownlint README.md
• clean CMake configure, build, and CTest cycle with --config Debug
• workflow and Dependabot YAML parsing
• VS Code task JSON parsing
• git diff --check origin/main

[snovalnikov]

Overall this is a solid refresh. The PR consistently updates the bootstrap to a zero-friction cross-platform setup: it pins and verifies GoogleTest, uses the same make test flow across OSes, keeps direct CMake/CTest paths for environments without Make, and clarifies setup expectations in the README. The CI workflow and Dependabot changes are also aligned with the project goals and don’t appear to introduce regressions. I don’t see a blocking issue in this patch. Approved.