The reasoning-effort tier (`max` chip + whale icon) and the live/context
indicators were the only signals on the right of the header. Switching
to nvidia-nim left the right-hand side identical to a DeepSeek session,
so it wasn't obvious at a glance that requests were going to a different
backend.
Now: when `app.api_provider != Deepseek`, the header surfaces a bold
`NIM` chip on the right, leftmost in the chip cluster (so it survives
the narrow-width fallback variants in `right_spans`). Default-DeepSeek
sessions are unchanged — `provider_label = None` short-circuits the
chip.
Closes#38.
Hunter Bown
07ae792068