POC: add documentation delta reporting to PR checks

[AlexanderLanin]

What this achieves

This POC adds an automated documentation delta report to pull requests and publishes the result as a PR comment alongside the documentation preview.

Why this is necessary

Documentation changes are currently difficult to review from generated output alone. A concise comparison of Sphinx-Needs data and rendered HTML makes affected requirements and pages visible directly in the pull request.

This is an exploratory POC and is not intended for merging.

[github-actions]

Documentation delta

Documentation preview for this pull request: open preview · Baseline: open baseline

Summary

• Needs: 0 added, 0 removed, 1 modified, 91 unchanged
• Rendered pages: 0 added, 0 removed, 3 modified, 50 unchanged

Need changes

Modified (1)

• doc_tool__score_docs_as_code — Doc-as-Code (old / new)
  • content: "Evaluates the S-CORE Docs-as-Code tool for building and checking\ndocumentation and traceability data from RST/Markdown sources." → "Evaluates the S-CORE Docs-as-Code tool for building and checking\ndocumentation and traceability data from RST/Markdown sources. It also\nsummarizes changed Needs between the published documentation and a pull\nrequest's proposed documentation."

Page changes

Modified (3)

• internals/requirements/requirement_coverage.html (old / new)
• internals/requirements/tool_verification.html (old / new)
• internals/requirements/tooling_verification.html (old / new)