Navbar layout inconsistency: issue #2414 fixed

[AyushPatiTripathi]

Summary

This PR fixes a layout inconsistency in the Documentation site header where the
navigation could wrap onto an extra line above the logo, creating unnecessary
vertical spacing. The issue was caused by a redundant Docs-specific header block
being rendered in addition to the global site header.

What changed

• Removed the redundant documentation-only header block
• Ensured the global site header is used consistently on Docs pages
• Prevented unintended flex wrapping at desktop widths

Notes on the theme toggle

While investigating this issue, I noticed that the light/dark mode toggle is not
present on the Issues site. After further inspection, the Issues pages are served
by Trac and do not share Django’s template stack or frontend assets.

I have not attempted to address this in this PR, as it appears to be outside
the scope of the Django site templates. I’m happy to open a follow-up issue or
work on this if there’s interest in coordinating a solution on the Trac side.

Screenshots / Verification

• Docs navbar remains on a single line at desktop widths
• No regression on the main site or other sections