Add e2e test for invalid PSBT upload

[harrshita123]

Follow-up to #462, which GitHub would not allow me to reopen from this account.

[changeset-bot]

⚠️ No Changeset found

Latest commit: fe798d5

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

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
caravan-coordinator	Ready	Preview, Comment	Jul 2, 2026 4:37pm

[harrshita123]

@bucko13 Could you please review this PR when you have a chance? This is the follow-up to #462, which GitHub would not allow me to reopen from my account.

[bucko13]

@bucko13 Could you please review this PR when you have a chance? This is the follow-up to #462, which GitHub would not allow me to reopen from my account.

Cc @Shadouts and @jpcummins who are leading up maintenance duties now.