🧪 [testing improvement] Add tests for AnchorUtilities::compute

[ineersa]

🎯 What: The AnchorUtilities::compute method, which is a pure static string processing function that computes anchor nesting depth information from HTML source, was previously lacking dedicated test coverage. This PR introduces a complete test suite for this method.

📊 Coverage: A new test class tests/AnchorUtilitiesTest.php is added. It utilizes a PHPUnit DataProvider to test various HTML scenarios, including:

• Plain text without anchors
• Single unnested anchors
• Nested anchors (<a href="1">link1 <a href="2">link2</a></a>)
• Multiple sibling anchors
• Anchors with attributes and uppercase tags (<A HREF="...">)
• Self-closing anchor tags (<a />)
• Malformed anchor tags (e.g., unclosed tags, extra closing tags)
• Complex mixed HTML content

✨ Result: The AnchorUtilities::compute method is now fully covered by unit tests, ensuring that the tokenization and depth calculations are correct and deterministic across multiple edge cases, preventing regressions without needing to run the entire conversion pipeline.

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PR created automatically by Jules for task 9215090781857165599 started by @ineersa

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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