Extract model catalog into a single models.md; point chat + API docs at it

README.md

@@ -11,6 +11,7 @@ funded through our [Open Collective](https://opencollective.com/inference-cooper
 ## Start here
 
 - **New here?** → [Getting started](getting-started.md) — join, use the chat, and get involved in governance.
+- **Which models can I use?** → [Models](models.md) — the full catalog of providers and models.
 - **Want API access?** → [API access](api-access.md) — use our models programmatically.
 - **Curious how it works?** → [Infrastructure](infrastructure.md) — a map of the stack and the codebase.