ci: notify Slack on regression failure in main

[Wodann]

If the HH3 regression benchmark run fails on a (merge) commit to main, a Slack notification will be sent to inform the team.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 8c5b597

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[Copilot]

Pull request overview

Adds a Slack notification to the HH3 regression benchmark workflow so the team is alerted when a baseline run on main fails.

Changes:

• Add a Slack notification step that runs only when the job fails and the run is a baseline (push to main).
• Send minimal context (workflow name and run URL) via the existing GH_ACTION_NOTIFICATIONS_SLACK_WEBHOOK_URL webhook trigger integration.

---

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.40%. Comparing base (7491446) to head (8c5b597).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1504      +/-   ##
==========================================
- Coverage   79.40%   79.40%   -0.01%     
==========================================
  Files         446      446              
  Lines       76607    76607              
  Branches    76607    76607              
==========================================
- Hits        60831    60830       -1     
  Misses      13656    13656              
- Partials     2120     2121       +1     

☔ View full report in Codecov by Harness.
📢 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.

[anaPerezGhiglia]

LGTM

[Wodann]

This PR doesn't alter the actual code, so the JS Solidity test runner benchmark regression is a false positive: https://github.com/NomicFoundation/edr/actions/runs/27998674617/job/82866323786?pr=1504