Add a ProviderType.OPENROUTER branch to ProviderRegistry._create_provider_llm()
so that create_llm("openrouter") returns a configured LangChain BaseLanguageModel
instead of raising ValueError("Unsupported provider type: openrouter").
The new branch creates a ChatOpenAI instance with openai_api_base set to the
OpenRouter gateway URL and openai_api_key from settings, matching the credentials
used by create_ai_provider(). Optional default_headers are sanitized to
dict[str, str] (string-coerced keys and values) via inline dict comprehension.
Also includes review fixes:
- M1: Added openrouter_organization header support (HTTP-Referer, X-Title)
- m1: Added explicit ValueError when openrouter_api_key is empty/missing
- M2: Added openai_api_key assertions to all OpenRouter BDD scenarios
- m2: Added default model fallback scenario for model_id=None
- m4: Added empty default_headers edge case scenario
- m5: Added extra kwargs forwarding scenario (temperature)
- m6: Added empty API key error scenario
- m7: Added negative assertion verifying original integer key 123 is absent
- m8: Added openai_api_key assertion to sanitized headers scenario
ISSUES CLOSED: #10948
hurui200320