fix(credential-status): plugin class missing OpenAPI schema

[0x62]

What issue is this PR fixing

credential-status plugin is missing a schema definition, causing it to crash the OpenAPI schema generator in @veramo/remote-client, so fails with remote agents.

What is being changed

Added schema

Quality

Check all that apply:

• [X] I want these changes to be integrated
• [X] I successfully ran pnpm i, pnpm build, pnpm test, pnpm test:browser locally.
• [X] I allow my PR to be updated by the reviewers (to speed up the review process).
• [ ] I added unit tests.
• [ ] I added integration tests.
• [X] I did not add automated tests because _____, and I am aware that a PR without tests will likely get rejected.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.72%. Comparing base (2f0b06d) to head (b4935d0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## next #1427 +/- ## ======================================= Coverage 89.72% 89.72% ======================================= Files 177 177 Lines 26818 26820 +2 Branches 2220 2220 ======================================= + Hits 24062 24064 +2 Misses 2756 2756 ```

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