chore(sidebar): use chevron for dropdown

[avivkeller]

cc @ovflowd @bjohansebas based on https://openjs-foundation.slack.com/archives/CVAMEJ4UV/p1783185935444279

[vercel]

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Project	Deployment	Actions	Updated (UTC)
nodejs-org	Ready	Preview	Jul 4, 2026 7:55pm

[cursor]

PR Summary

Low Risk
Presentational sidebar UI only; no routing, data, or auth changes.

Overview
Nested sidebar sections that use <details> now show a chevron beside the label so expand/collapse is clearer.

The icon uses new .chevron styles: neutral by default, brand color and 180° rotation when the group is open, with a motion-safe transform transition. Behavior (auto-open when a child route is active) is unchanged.

^{Reviewed by Cursor Bugbot for commit bfcfe67. Bugbot is set up for automated code reviews on this repo. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.41%. Comparing base (a5b11b7) to head (bfcfe67).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8997      +/-   ##
==========================================
+ Coverage   75.39%   75.41%   +0.02%     
==========================================
  Files          98       98              
  Lines        8636     8636              
  Branches      318      318              
==========================================
+ Hits         6511     6513       +2     
+ Misses       2121     2119       -2     
  Partials        4        4              

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[Copilot]

Pull request overview

Updates the SidebarGroup UI so expandable sidebar subgroups use a consistent chevron icon indicator (instead of the native disclosure marker), matching the visual affordance used by other dropdown-like components in ui-components.

Changes:

• Add a ChevronDownIcon to subgroup <summary> elements in SidebarGroup.
• Style the chevron (size/color) and rotate it when the <details> is open.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/ui-components/src/Containers/Sidebar/SidebarGroup/index.tsx	Renders a chevron icon alongside subgroup labels in the <summary>.
packages/ui-components/src/Containers/Sidebar/SidebarGroup/index.module.css	Adds chevron styling and rotates it in the [open] state.

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[github-actions]

Lighthouse Results

URL	Performance	Accessibility	Best Practices	SEO	Report
/en	🟢 94	🟢 93	🟢 96	🟢 100	🔗
/en/about	🟢 100	🟢 94	🟢 96	🟠 88	🔗
/en/about/previous-releases	🟢 99	🟢 97	🟢 96	🟢 100	🔗
/en/download	🟢 99	🟢 96	🟠 81	🟢 100	🔗
/en/download/archive/current	🟢 100	🟢 97	🟢 100	🟢 100	🔗
/en/blog	🟢 100	🟢 97	🟢 96	🟢 100	🔗

[AugustinMauroy]

LGTM !

[bjohansebas]

By the way, it was LGTM as well. It looks like I just never submitted the review :)