[AI-5800] Measure size of dependencies before PRs are merged

[lucia-sb]

What does this PR do?

Adds logic that uploads dependency size data to a JSON artifact, so size measurements no longer depend on merged lockfiles.

Motivation

Size measuraments are inaccurate because dependency lockfiles are merged in a follow-up PR. As a result, updates or new dependencies aren’t reflected in the size delta of the originating PR.
This change uploads dependency sizes as a JSON artifact during the build, allowing us to measure size changes directly, without relying on lockfile merges.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[github-actions]

⚠️ Recommendation: Add qa/skip-qa Label

This PR does not modify any files shipped with the agent.

To help streamline the release process, please consider adding the qa/skip-qa label if these changes do not require QA testing.

[codecov]

Codecov Report

❌ Patch coverage is 68.57143% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.00%. Comparing base (9edf24e) to head (132d3d3).
⚠️ Report is 31 commits behind head on master.

Additional details and impacted files

🚀 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.