Complete Definition-of-Done blockers and update quality tooling

[TristanKruse]

Makes the prototype ready for users: the README quickstart runs against a passing and failing project, the generated documentation has a curated API guide and validated navigation, and the repository includes the Ruby family logo and community/security/contribution information.

• Preserve the completed Definition-of-Done fixes, including the trailing-folder-glob correction and its regression coverage.
• Sync with the merged documentation-rendering and debug-inspection PRs (Fix generated documentation rendering #52 and Add detailed check inspection and prepare Ruby 0.0.2 #53). Keep their new examples rendered correctly and label the prepared 0.0.2 changelog as unreleased.
• Include Dependabot's RuboCop 1.90.0 update from Bump rubocop from 1.89.0 to 1.90.0 in the minor-and-patch group #50, plus the 12 comment-only suppression changes needed by its new Style/DirectiveScope rule. The corrected standalone Bump rubocop from 1.89.0 to 1.90.0 in the minor-and-patch group #50 passed all five CI jobs, but GitHub still reported a qualifying review was required despite the submitted approval. Its changes are preserved here for Lukas's review rather than bypassing that requirement.
• Keep the extraction enhancements in separate PR Resolve constant-reference dependencies and safely inferred import paths #56, based on this branch. Review and merge this PR first, then retarget Resolve constant-reference dependencies and safely inferred import paths #56 to main if GitHub has not done so automatically. Overlapping edits have already been resolved, and their combined changes are also checked before handoff.

Local validation on Ruby 4.0.6 / Windows: 463 examples, zero failures (one existing symlink-capability skip); 98.99% line and 90.83% branch coverage. RuboCop inspects 239 files with no offenses. The documentation build validates the API guide and internal links, and the strict 0.0.2 gem build passes. All five GitHub CI jobs pass, covering the supported Ruby/OS matrix, packaging, and the downstream RAG fixture. The combined branch with #56 also passes 499 examples with zero failures.

No RubyGems publication is triggered by this PR. Release remains a separate manually dispatched workflow.

[TristanKruse]

Owner follow-up after merge (requires ADMIN, while Tristan currently has WRITE): set the repository website to https://lukasniessen.github.io/ArchUnitRuby/; upload assets/social-preview.png under Settings > General > Social preview; and enable Private vulnerability reporting under Settings > Security so the SECURITY.md disclosure link works. All PR checks are green.