WIP: Add contract admin dashboard

[jkachel]

What are the relevant tickets?

mitodl/hq#11077

Description (What does it do?)

This adds the components necessary to display the enrollment codes to designated users within Learn.

Screenshots (if appropriate):

• Desktop screenshots
• Mobile width screenshots

How can this be tested?

1. Create a contract of "code" or "non-sso" type. Add courseware to it, and run b2b_codes validate --fix so there are codes to look at.
2. Attach a user to the org and contract. Update the user's membership to set the Manager flag to True.
3. Load the dashboard for the contract in Learn. You should see a link to the admin.
4. Click the admin link. You should see codes and should be able to do some basic functions with them.

Additional Context

Did a bunch of the heavy lifting for this with Claude Opus 4.7 and probably some other things because that turned out to be pretty expensive. But this probably needs some extra scrutiny because of that.

[github-actions]

OpenAPI Changes

No changes to report, but the specs are different

View full changelog

Unexpected changes? Ensure your branch is up-to-date with main (consider rebasing).