fix(AIC-3382): support Bedrock configs in LangChain handlers

[andrewklatzke]

Summary

TypeScript counterpart to launchdarkly/python-ai-sdk#101. Three fixes for LangChain handlers (langchain-agents and langchain-messages):

• Bedrock configs with no explicit llm now instantiate @langchain/aws's ChatBedrockConverse instead of falling through to ChatOpenAI. Model parameters and the region-prefixed model ID are forwarded. @langchain/aws is an optional peer dependency, with a clear install error when absent.
• For Bedrock, model.region is prepended to the model ID as an inference-profile prefix. Prefixing is idempotent and applies to default constructors and user-supplied factories without mutating the caller's config.
• gen_ai.provider.name now reports the configured provider lower-cased rather than collapsing non-Anthropic providers to OpenAI. gen_ai.system remains langchain.

The streaming example also falls back to the final response when no chunk events are emitted.

Test plan

• Unit tests for both LangChain handlers, including Bedrock default construction, region prefixing, and factory config handling
• Integration scenarios for success and failure paths
• Biome and TypeScript checks

Jira: AIC-3382

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Note

Overview
Adds AWS Bedrock as a first-class default model path for the langchain-agents and langchain-messages handlers: Bedrock configs without a custom llm now build ChatBedrockConverse via dynamic @langchain/aws import (optional peer; clear error if missing).

Bedrock model IDs get model.region prepended once as an inference-profile prefix (us.model…), without double-prefixing or mutating the caller’s config; factories receive a shallow copy with the resolved name. Bedrock constructor args drop tools from model.parameters so tool wiring stays on the agent/handler side.

OpenTelemetry gen_ai.provider.name is now the configured provider name lower-cased (empty → openai), not only anthropic vs openai; gen_ai.system stays langchain.

The streaming example prints the final response when no chunk events arrive, and logs usage/judge results on stdout instead of stderr debug noise.

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[XieX]

Is it enough to just lowercase them, or should we add a mapping function? Obviously Anthropic -> anthropic and OpenAI -> openai will be fine, but what about some of the others, like "IBM Watson"?

[andrewklatzke]

This is just for the telemetry information, so I think that should be fine

[andrewklatzke]

Confirmed bedrock call via langchain in my sample app with my orchestrator