[BUG] Bedrock streaming drops native tool calls, so the tool never runs

Description

With a Bedrock model and streaming on (LLM(..., stream=True), or Crew(stream=True)), native tool calls are dropped. The tool never runs, and the task's answer becomes "I apologize, but I couldn't generate a response. Please try again." No error is raised.

The agent executor calls the LLM with available_functions=None and runs the returned tool calls itself. _handle_converse returns the tool uses in that case, but _handle_streaming_converse and _ahandle_streaming_converse only use a tool call when available_functions is set, then throw it away. The stream has no text, so the empty-content fallback string is returned as the final answer.

Steps to Reproduce

1. Create an agent with a Bedrock LLM (stream=True) and one tool.
2. Mock converse_stream to return a toolUse block, then a text answer on the next call.
3. Kick off a crew with one task for that agent.

Expected behavior

Same as stream=False: the tool runs and the crew returns the model's answer.

Screenshots/Code snippets

stream=False tool ran with=['Paris'] final answer='It is sunny in Paris.'
stream=True  tool ran with=[]        final answer="I apologize, but I couldn't generate a response. Please try again."

The Converse stream events are the same shape as _make_tool_use_stream() in tests/llms/bedrock/test_bedrock_streaming_tool_args.py.

Operating System

macOS

Python Version

3.12

crewAI Version

1.15.21 (main at 894898f)

crewAI Tools Version

not used

Virtual Environment

uv venv

Evidence

Non-streaming returns the calls at bedrock/completion.py:741-752. The streaming handlers only use them under if available_functions: (sync at 1096, async at 1707), and the executor always passes available_functions=None (experimental/agent_executor.py:1567). #6150 fixed the streamed arguments, but its tests always pass available_functions, so this path isn't covered.

Possible Solution

When available_functions is empty, collect the parsed tool uses in the streaming handlers and return them after the stream ends, the way the non-streaming path does. I have a fix with tests and will open a PR.

Additional context

This issue was written with AI assistance (Claude Code). I can't add the llm-generated label as an outside contributor; could a maintainer add it?

Start in bedrock/completion.py at the streaming handlers around lines 1096 and 1707, then compare their behavior with the non-streaming path at lines 741-752 and the executor call in experimental/agent_executor.py:1567. Use the Converse stream shape from tests/llms/bedrock/test_bedrock_streaming_tool_args.py and verify both sync and async streaming return tool uses when available_functions is None, then confirm the tool runs and the final answer matches the non-streaming case.