feat: use new assistant theme

[luka-nextcloud]

📝 Summary

• Resolves: #
  Apply new assistant theme colors

🖼️ Screenshots

🏚️ Before	🏡 After

🏁 Checklist

• Code is properly formatted (npm run lint / npm run stylelint / composer run cs:check)
• Sign-off message is added to all commits
• Tests (unit, integration and/or end-to-end) passing and the changes are covered with tests
• Documentation (README or documentation) has been updated or is not required

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.71%. Comparing base (d7f31be) to head (5995a21).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7622      +/-   ##
==========================================
+ Coverage   52.94%   59.71%   +6.76%     
==========================================
  Files         503      502       -1     
  Lines       43796    38859    -4937     
  Branches     1129     1128       -1     
==========================================
+ Hits        23189    23203      +14     
+ Misses      20498    15548    -4950     
+ Partials      109      108       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[enjeck]

lgtm