👷 Split unit-bs CI job per browser

[mormubis]

Motivation

The unit-bs job runs all 5 browsers in a single Karma process. If one browser is unavailable on BrowserStack, the whole job fails and you lose the results from the other 4.

Changes

Each browser now runs as a separate CI job using parallel: matrix. The --browser flag on ci-bs.ts filters the Karma config to a single browser. Resource groups are per-browser so they don't serialize against each other. JUnit reports are written to per-browser directories to avoid collisions. Without --browser, all 5 browsers run as before.

Test instructions

BS_BROWSER=edge yarn test:unit:bs        # Only Edge launches
BS_BROWSER=nonexistent yarn test:unit:bs  # Throws with available ids
yarn test:unit:bs                         # All 5 browsers (backwards compat)

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.
• Updated documentation and/or relevant AGENTS.md file

[cit-pr-commenter-54b7da]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	169.51 KiB	169.51 KiB	0 B	0.00%	✅
Rum Profiler	5.97 KiB	5.97 KiB	0 B	0.00%	✅
Rum Recorder	21.23 KiB	21.23 KiB	0 B	0.00%	✅
Logs	54.70 KiB	54.70 KiB	0 B	0.00%	✅
Rum Slim	127.85 KiB	127.85 KiB	0 B	0.00%	✅
Worker	22.99 KiB	22.99 KiB	0 B	0.00%	✅

🚀 CPU Performance

Pending...

🧠 Memory Performance

Pending...

🔗 RealWorld

[datadog-official]

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 76.96% (+0.00%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: e0a2b44 | Docs | Datadog PR Page | Give us feedback!}