Codex 5th CORE: the ownership set only covered static _PROVIDER_MODELS, not the
active provider's own config.yaml providers.<active>.models allowlist. So an
active provider defined purely via providers: (no static catalog) could be
hijacked by another slug's overlapping entry earlier in config order. Fix folds
the active provider's own providers: allowlist (list + dict shapes, copilot
excluded) into _provider_models_set — completing the ownership model so the
active provider owns its declared models from EITHER the static catalog OR its
own providers: entry. Regression test (fail-without-fix verified). 40 model_resolver
tests green.
Co-authored-by: akay64 <akay64@users.noreply.github.com>
