Bundle size comparison script

[TommyBrosman]

Adds a script for comparing the bundle size for two revisions.

Description

A concise description of the changes (bug or feature) and their impact/motivation.
If this description is short enough to be used as the title, delete this section and just use the title.

For bug fixes, also include specifics of how to reproduce it / confirm it is fixed.

If this Pull Request should close/resolve any issues when merged, use the special syntax for that here.

Breaking Changes

If this introduces a breaking change, please describe the impact and migration path for existing applications below.
See Breaking-vs-Non-breaking-Changes for details.
If there are no breaking changes, delete this section.

Reviewer Guidance

The review process is outlined on this wiki page.

List any specific things you want to get reviewer opinions on, and anything a reviewer would need to know to review this PR effectively.
Things you might want to include:

• Questions about how to properly make automated tests for your changes.
• Questions about design choices you made.
• Descriptions of how to manually test the changes (and how much of that you have done).
• etc.

If you have any questions in this section, consider making the PR a draft until all questions have been resolved.

[github-actions]

Hey! You look nice today! Want me to review this PR?

Based on the diff (1476 lines, 6 files), I've queued these reviewers:

• Correctness — logic errors, race conditions, lifecycle issues
• Security — vulnerabilities, secret exposure, injection
• API Compatibility — breaking changes, release tags, type design
• Performance — algorithmic regressions, memory leaks
• Testing — coverage gaps, hollow tests

Toggle checkboxes to adjust, then reply yes to start — or ask me anything!