Remove obsolete Doxygen and Sphinx documentation tooling

[bdice]

cuVS builds its documentation with Fern, whose API generator reads source files directly rather than consuming Doxygen XML.

• Remove unused cpp/doxygen/ assets and stale CI, lint, and ignore rules.
• Update contributor instructions, documentation links, and CodeRabbit guidance for Fern.
• Reduce docs-only dependencies to Python and Node.js, leaving build/test environments unchanged.

Doxygen-style source comments and Sphinx-role parsing remain in use and are preserved. No public API or generated API content changes.

Supersedes #2609.

[bdice]

I'm fine with keeping or removing this sentence. Up to reviewers.

Suggested change

The API generator reads source files directly, including Doxygen-style C/C++ comments and Sphinx-style roles in Python docstrings. It does not require the Doxygen or Sphinx executables or generated XML.

[KyleFromNVIDIA]

Let's leave it in

[KyleFromNVIDIA]

Let's leave it in

[dantegd]

Cleanup looks good to me

[cjnolet]

/merge

[coderabbitai]

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📒 Files selected for processing (12)

• .coderabbit.yaml
• .github/workflows/pr.yaml
• .gitignore
• .pre-commit-config.yaml
• README.md
• cpp/doxygen/Doxyfile
• cpp/doxygen/header.html
• cpp/doxygen/main_page.md
• dependencies.yaml
• fern/README.md
• fern/pages/c_guidelines.md
• fern/pages/cpp_guidelines.md

💤 Files with no reviewable changes (6)

• cpp/doxygen/main_page.md
• dependencies.yaml
• cpp/doxygen/header.html
• .gitignore
• .github/workflows/pr.yaml
• .pre-commit-config.yaml

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📝 Summary

Summary by CodeRabbit

• Documentation
  • Updated contributor and developer guidance to describe how API references are generated from source comments and how to validate documentation.
  • Updated links to the contributor and developer guides.
  • Removed the Doxygen HTML header template and main-page description.
• Chores
  • Updated review guidance and pull-request checks to reflect the current documentation locations and include matching Doxygen-related changes in Python test filters.

Walkthrough

The pull request updates contributor and review guidance to use Fern for API documentation. It removes Doxygen-related files and environment entries, changes CI path filters, and updates ignore and copyright-hook configuration.

Changes

Fern API documentation transition

Layer / File(s)	Summary
Fern API authoring and review guidance .coderabbit.yaml, README.md, fern/README.md, fern/pages/c_guidelines.md, fern/pages/cpp_guidelines.md	Review instructions and contributor links now target Fern. The guides describe Doxygen-style source comments consumed by the Fern API generator and replace Doxygen checks with Fern API-reference and documentation checks.
Documentation tooling and validation configuration .github/workflows/pr.yaml, .gitignore, .pre-commit-config.yaml, cpp/doxygen/*, dependencies.yaml	The CI filters no longer exclude cpp/doxygen/**. The Doxygen header and main page are removed, the docs environment drops several includes, and Doxygen-related ignore entries are removed. The copyright hook configuration changes for github_link.py.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Other

Suggested reviewers: imotov

Merge Risk: ⚪ Minimal · up to 53c7b

The PR removes obsolete documentation tooling while retaining Fern documentation support. No new user-facing or release risk is substantiated, so it is ready to merge after normal checks.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the removal of obsolete Doxygen and Sphinx documentation tooling, which is the main change.
Description check	✅ Passed	The description explains the tooling removal, related documentation and CI updates, and the continued use of Doxygen-style comments and Sphinx-role parsing.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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