fix(AIC-3506): strip tools from LangChain model constructor kwargs

[andrewklatzke]

Human explanation:

Strips model.parameter.tools off of Langchain handlers so they don't get splatted into the kwargs. model.parameters.tools is a copy of the existing tools left in for backwards compatibility.

AI explanation:

Tools in model.parameters are forwarded raw and rejected by the provider API. They are already bound from the top-level tools field.

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Note

Overview
Strips tools from LangChain chat model constructor kwargs everywhere default models are built, not only on Bedrock.

model.parameters.tools is a backwards-compat mirror of top-level config["tools"]. Forwarding it into ChatOpenAI / ChatAnthropic / ChatBedrockConverse caused provider errors because tools are already bound via bind_tools / agent setup. _model_constructor_kwargs in langchain-agents and langchain-messages now always pop("tools"); native_graph does the same for the default per-node ChatOpenAI path.

Tests assert constructors receive temperature, max_tokens, and model name only—no tools in the kwargs bag.

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