Consolidated branch work: modernize the CMake layout and developer workflow,
expand GitLab CI for multiple OS images and Docker, and align documentation
and tooling with the new pipeline for the graph library.

Build / CMake
- Refactor CMake presets and module layout; wire examples and tests; align
  with shared CI/script conventions.

CI / GitLab
- Multi-OS matrix and per-OS jobs, workflow rules (tags, MR, default branch),
  draft-MR skip, secondary OS matrix gating.
- Docker: build/push helpers, context-unchanged skip, Harbor login (stdin,
  fallbacks, protected-variable hints), dind/network fixes for runners.
- Quality: lint/static-analysis/coverage/sanitize scripts, lcov and tooling
  alignment with the generator project.
- Release/suggest-version scripting and related CI glue.

Documentation
- Doxygen/m.css pipeline, local build-docs.sh, bilingual doc structure,
  README and setup guides (install-deps per OS).
- Comment an...