fix: conversation details focus traversal order [WPB-14810]

[Garzas]

https://wearezeta.atlassian.net/browse/WPB-14810

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PR Submission Checklist for internal contributors

• The PR Title

  • conforms to the style of semantic commits messages¹ supported in Wire's Github Workflow²
  • contains a reference JIRA issue number like SQPIT-764
  • answers the question: If merged, this PR will: ... ³

• The PR Description

  • is free of optional paragraphs and you have filled the relevant parts to the best of your ability

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What's new in this PR?

• Fixes keyboard focus traversal in conversation details
• Groups the collapsing top bar focus targets so Search and Media are reached before the tab row
• Reuses a single collected loading state in the screen content

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 51.71%. Comparing base (eae3b00) to head (eba5fa6).
⚠️ Report is 3 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4886      +/-   ##
===========================================
- Coverage    51.87%   51.71%   -0.17%     
===========================================
  Files          614      616       +2     
  Lines        21297    21454     +157     
  Branches      3417     3422       +5     
===========================================
+ Hits         11047    11094      +47     
- Misses        9226     9334     +108     
- Partials      1024     1026       +2     

see 28 files with indirect coverage changes

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