feat(duo_workflows): resolve the model dimension to catalog metadata

The model dimension compiles to the raw modelUsed string today, so charts label bars with gateway refs and provider-resolved ids. This selects the model object from gitlab!256020 (merged) instead: name, provider, hosting, and isDefault, resolved server side against the model catalog. Sorting moves to the model identifier, which groups on the same expression.

Two ordering notes: gitlab!256020 (merged) must merge before this releases, and the frontend needs its object label formatter registered before the npm bump lands, or model chart labels render blank. That frontend MR follows.

Validated with the duo_workflows compile tests; full suite green.

Related to gitlab-org/gitlab&23470.