Docs heading outline skips from H1 to H3 on two pages

[Alek99]

Summary

Two production documentation pages skip directly from a page H1 to an H3, weakening the document outline for assistive technology and generated navigation.

Verified on the production build for main at d505ef5789d8b18e23fd838300b039932dc399ce.

Affected pages

Page	First invalid jump
/docs/xy/components/modebars-and-interaction-controls/	H1 to H3: The default toolbar
/docs/xy/overview/benchmarks/	H1 to H3: Live interactive render time

The Modebars page authors ### The default toolbar before its first H2. The Benchmarks jump is introduced by visible rendered demo content before the first authored H2.

Expected behavior

Visible headings increase by at most one level and reflect the actual section hierarchy.

Acceptance criteria

• Correct the Modebars authored heading levels.
• Give the benchmark demo heading a level consistent with the page outline, or remove heading semantics if it is only chart chrome.
• Preserve TOC depth and visual styling.
• Add an all-public-route heading-jump regression check.