fix(models): Add non-streaming support to OpenAIModel

[Ratish1]

Description

This pull request adds support for non-streaming responses to the OpenAIModel. Users can now set streaming=False during model initialization to receive a single, complete response object instead of an event stream.

Key Changes

src/strands/models/openai.py:

• Added optional streaming: Optional[bool] config key.

• format_request now respects streaming (defaults to True to preserve existing behavior).

• Stream method supports both streaming and non-streaming flows (converts non-streaming provider response into streaming-style events).

• Small helper _convert_non_streaming_to_streaming added to normalize non-streaming responses into the same event format.

src/strands/models/litellm.py:

• Updated to include a streaming option in its config and to preserve compatibility with OpenAIModel.

tests/strands/models/test_openai.py:

• Updated/added tests to cover non-streaming behavior.

Related Issues

Closes #778

Documentation PR

N/A

Type of Change

Bug fix

Testing

How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

• [ ] I ran hatch run prepare
• [x] I ran hatch fmt --formatter locally.
• [x] I ran hatch fmt --linter and pre-commit run --all-files.
• [x] I ran unit tests locally:
• tests/strands/models/test_openai.py::test_stream → Passed
• tests/strands/models/test_openai.py::test_stream_respects_streaming_flag → Passed

Checklist

• [x] I have read the CONTRIBUTING document
• [x] I have added any necessary tests that prove my fix is effective or my feature works
• [ ] I have updated the documentation accordingly
• [ ] I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• [x] My changes generate no new warnings
• [x] Any dependent changes have been merged and published

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