Layout: sidebar scroll anchor

[maximusmith529]

Proposed changes

This PR adds functionality to the sidebar that allows it to move to the user's location in the docs on page load or reload. This helps with long lists or nested docs. This is in relevance to issue 578

Here I've got a video showcasing the changes. I navigate to a nested link, click on it and scroll up, then reload the page to show that it navigates back to the link. Then I show how it will try to bring the link to the top if possible.

Screen.Recording.2025-09-09.at.10.45.27.AM.mov

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• I have updated any relevant documentation (README.md and CHANGELOG.md)

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