- Return InvalidRequest (400) for unsupported speed too, matching the
reasoning_effort check and the complete()/stream() doc comments
- Centralize fabro_llm::Error -> ApiError mapping in a From impl so the
completions handler, playground handler, and Error::Llm arm agree on
the InvalidRequest -> 400 / else -> 502 split
- Reject unparseable reasoning_effort values with 400 instead of
silently dropping them
- Add classify_sdk_invalid_request test per fabro-workflow convention
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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