Sync updates from stainless branch: ehhuang_dev

[ehhuang]

What does this PR do?

Sync stainless sdk

Test Plan

# llama-stack-client-python
uv pip install -e . 
cd llama-stack
uv pip install -e .

LLAMA_STACK_CONFIG=fireworks pytest -s -v tests/client-sdk/  --safety-shield meta-llama/Llama-Guard-3-8B

Outputs:
======================================= short test summary info =======================================
FAILED tests/client-sdk/agents/test_agents.py::test_override_system_message_behavior[meta-llama/Llama-3.1-8B-Instruct] - assert 'function' in 'shield_call> No Violationinference> "Why did the bicycle fall over? Because ...
================== 1 failed, 32 passed, 3 skipped, 115 warnings in 64.37s (0:01:04) ===================

1 Tests fail on both head and base. test_override_system_message_behavior is a bit flaky; passed with

LLAMA_STACK_CONFIG=fireworks pytest \-\-inference\-model=meta\-llama/Llama\-3\.3\-70B\-Instruct -s -v tests/client-sdk/agents/test_agents.py::test_override_system_message_behavior

will look into fixing this test

Sources

Please link relevant resources if necessary.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Ran pre-commit to handle lint / formatting issues.
• Read the contributor guideline,
  Pull Request section?
• Updated relevant documentation.
• Wrote necessary unit or integration tests.