#28585 Agents page can hit 422 from /key/list page size limit
## Summary
The Agents dashboard can fail while fetching key metadata because the UI calls `/key/list` with a page size larger than the backend accepts.
## Symptom
A downstream deployment observed the Agents page request failing with `422 Unprocessable Content` for:
`GET /key/list?page=1&size=500&return_full_object=true&include_team_keys=true&include_created_by_keys=true`
The backend route validates `size` with a maximum of `100`, so `size=500` is rejected before the key-list response can be returned.
## Fix PR
PR: https://github.com/BerriAI/litellm/pull/28578
The PR: - changes the dashboard key lookup page size to `100` - paginates `/key/list` until all visible agent keys are found or all pages are exhausted - adds regression coverage for the page size and pagination behavior - keeps dependencies and lockfiles unchanged
Current PR status at the time of filing: - GitHub Actions pass - Veria AI - PR Review passes - PR is mergeable - local `npm audit signatures` passed
cc @krrish-berri-2 because recent Agents dashboard work points to that area of ownership.