docs: move theme button to menu

[UziTech]

Description

Move the light/dark theme button to the menu. No need to have it in a fix position.

Always show the GitHub banner so it is easier to get to the GitHub repo on mobile.

Contributor

• Test(s) exist to ensure functionality and minimize regression (if no tests added, list tests covering this PR); or,
• no tests required for this PR.
• If submitting new feature, it has been documented in the appropriate places.

Committer

In most cases, this should be a different person than the contributor.

• CI is green (no forced merge required).
• Squash and Merge PR following conventional commit guidelines.

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Project	Deployment	Actions	Updated (UTC)
marked-website	Ready	Preview	Aug 4, 2026 4:27am