feat: ✨ AWS Bedrock Provider tool streaming

[chezsmithy]

Description

Enable tool streaming for the AWS Bedrock provider (note we had some confusion with the openai-adapter code previously which has already been updated).

Some time back the tool code was revised to support streaming tool call output and this takes advantage of this change.

When the model is claude, we are also enabling the fine grained tool call beta header to speed up tool output to not wait for matching JSON end tags for streaming. Beta headers are ignored when no longer applicable and are only enabled for claude models.

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Checklist

• I've read the contributing guide
• The relevant docs, if any, have been updated or created
• The relevant tests, if any, have been updated or created

Screen recording or screenshot

[ When applicable, please include a short screen recording or screenshot - this makes it much easier for us as contributors to review and understand your changes. See this PR as a good example. ]

Tests

Manual testing performed to validate changes. Visually noting that on file creation and edit activities for example the user receives feedback/output much faster. Before this change the provider is building the entire tool call payload before sending any data.

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Summary by cubic

Enable streaming tool calls for the AWS Bedrock provider so tool output arrives incrementally instead of after full JSON completion. For Claude models, enable fine-grained tool streaming to reduce latency.

• New Features

  • Stream tool calls via ConverseStream: emit toolCalls on start and as input deltas arrive.
  • Enable Claude’s fine-grained tool streaming (anthropic_beta: fine-grained-tool-streaming-2025-05-14); ignored for non-Claude models.
  • Stream reasoning content, including text, signatures, and redacted thinking.

• Refactors

  • Remove internal tool input accumulation; rely on Bedrock content block start/delta events.
  • Consolidate event parsing for ContentBlockStart/Delta and ToolUseBlock/Delta to simplify streaming.