extraParams.provider was silently dropped by createStreamFnWithExtraParams().
This change injects it into model.compat.openRouterRouting so pi-ai's
buildParams includes params.provider in the API request body.
Enables OpenRouter provider routing options (only, order, allow_fallbacks,
data_collection, ignore, sort, quantizations) via model config:
```jsonc
"openrouter/model-name": {
"params": {
"provider": {
"only": ["deepinfra", "fireworks"],
"allow_fallbacks": false
}
}
}
```
Closes#10869✍️ Author: Claude Code with @carrotRakko (AI-written, human-approved)
415686244a