Bootstrap architecture docs and add reveal.js support

[dieterbaier]

Summary

This PR packages the architecture documentation bootstrap and the toolbox presentation support in two commits.

• Adds toolkit-compatible architecture documentation, AI contracts, validation, local build.sh, and GitHub Actions for PR validation and GitHub Pages publishing.
• Updates the toolbox image to include the Ruby asciidoctor-revealjs CLI so downstream projects can build Reveal.js presentations from .adoc sources.
• Documents direct Asciidoctor CLI usage, diagram rendering, Gradle/AsciidoctorJ usage, dogfooding of this repository's architecture build, and Reveal.js slide generation with explicit revealjsdir.

Impact

Downstream projects such as profile-dieterbaier can use the toolbox image for HTML architecture documentation, PlantUML diagram rendering, Gradle/AsciidoctorJ builds, and Reveal.js presentation builds from AsciiDoc.

Validation

• ruby scripts/validate-metamodel.rb --generate
• podman build -t docs-toolbox-test:reveal .
• podman run --rm docs-toolbox-test:reveal ... asciidoctor-revealjs --version ...
• ./build.sh build

Notes

The image provides the asciidoctor-revealjs converter. Reveal.js frontend assets are referenced via revealjsdir, either through a CDN or project-local vendored assets. Whether the toolbox should bundle Reveal.js assets is recorded as an open architecture decision candidate.

[dieterbaier]

The PR is mergeable. There is a weak point at the validator. This does not need to be addressed in the project, but rather at the architecture-knowledge-toolkit. There we opened Issue #48 for that.