Speed up CI workflow

[leehack]

Summary

• Split Chrome tests into a separate CI job so they run in parallel with the VM coverage job.
• Keep VM coverage generation, LCOV formatting, threshold checking, and Codecov upload unchanged.
• Trim the docs build job by removing unnecessary Flutter setup and enabling npm cache for the website lockfile.
• Add an aggregate Test Linux & Web (with Coverage) job that depends on both VM coverage and Chrome tests, preserving the old check name for branch protection.

Validation

• git diff --check
• ruby -e "require 'yaml'; YAML.load_file('.github/workflows/ci.yml'); puts 'yaml ok'"

[Copilot]

Pull request overview

Splits the combined Linux VM + Chrome test job into parallel jobs to speed up CI, trims the docs-check job, and preserves the original required check name via an aggregate job for branch protection compatibility.

Changes:

• Split test-linux-coverage (VM + coverage) and new test-web (Chrome) so they run in parallel; add aggregate test-linux-web that depends on both and keeps the legacy check name.
• Remove unnecessary Flutter setup/flutter pub get from docs-check and enable npm caching via website/package-lock.json.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.55%. Comparing base (2b184d9) to head (7efeb8b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #186   +/-   ##
=======================================
  Coverage   80.55%   80.55%           
=======================================
  Files          85       85           
  Lines       11380    11380           
=======================================
  Hits         9167     9167           
  Misses       2213     2213           

Flag	Coverage Δ
unittests	80.55% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ 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.