docs: respect system colorscheme

[NiclasvanEyk]

Change Summary

Screen.Recording.2024-10-20.at.22.45.41.mov

The left browser window shows the current version of the docs, the right one contains the changes from this PR

This PR makes the docs respect the systems color preference by default. As can be seen in the video, it currently defaults to light mode, even if I've set my OS to dark mode.

This also adds a new option to the theme picker next to the search. This means the cycle is now

• "auto" (default)
• "always light"
• "always dark"

Related issue number

Not an issue, but the dark mode seems to have been introduced in #2913. The convention that the button icon and alt text reflects the action instead of the current state is retained. The latest comment on the referenced PR also indicates that other users also expect the systems color preference to be the default.

Other Related Things

Here is a link to the docs of Mkdocs Material, where they describe the automatic dark/light mode: https://squidfunk.github.io/mkdocs-material/setup/changing-the-colors/#automatic-light-dark-mode

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

Selected Reviewer: @sydney-runkle

[codspeed-hq]

CodSpeed Performance Report

Merging #10667 will not alter performance

_{Comparing NiclasvanEyk:use-system-colorscheme-by-default (9735149) with main (06a04b5)}

Summary

✅ 44 untouched benchmarks

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[NiclasvanEyk]

please review

[Viicos]

Thanks for adding the video example. This looks good