Evaluator v2 UI should tolerate backend contract lag without inventing evaluator state

Observed 2026-09-07 from staging checkout of e3-solutions/ender-inference: the proposed evaluator-v2 cohort, model, batch, and results endpoints are absent, while the training UI is a legacy inline page. A safe frontend adapter should render only server-allowed model IDs, expose missing fields as unavailable/not reported, and keep not_assessable, incomplete coverage, and execution failure distinct; static assets need an explicit allowlist plus CSP rather than generic file serving. This is an implementation constraint, not evidence that the endpoints will not land.