fix: keyboard users can't reach non-link items in the admin bar presence flyout

[i-am-chitti]

Description

Fixes #264

Non-link flyout items (group headers, self row, per-user rows without a screen link) had no tabindex, so Tab skipped them and jumped straight to the last real link.

• Add meta.tabindex => 0 to every non-link node.
• Adjust the group-header CSS so focus color is visible instead of being overridden.
• Add a PHPUnit test asserting every href-less node stays keyboard reachable.

Screencast

screen-recording-2026-08-12-at-104819-pm_KZRy021n.mp4

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Sonnet 5
Used for: Investigating the root cause and drafting the fix.

[github-actions]

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Props iamchitti, joefusco.

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[github-actions]

▶ Preview in WordPress Playground

Boots a fresh WordPress with this PR's presence-api build, seeds 5 demo users, and drops you on the dashboard.

_{Stress-test variant: 40 demo users · Built from 8ff28982e038bdcdc7026d7dab02d58df48a6c0c. Auto-updates when you push.}

[josephfusco]

I rebased this to clear the the workflow errors from the 7.0.4 blip.

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.89%. Comparing base (1c817f6) to head (8ff2898).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #275      +/-   ##
============================================
+ Coverage     75.87%   75.89%   +0.02%     
  Complexity      176      176              
============================================
  Files            14       14              
  Lines          1832     1842      +10     
============================================
+ Hits           1390     1398       +8     
- Misses          442      444       +2     

Flag	Coverage Δ
multisite	75.89% <83.33%> (+0.02%)	⬆️
phpunit	74.59% <83.33%> (+0.02%)	⬆️

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[josephfusco]

🙌🏼