Agent response format

[hanzlfs]

What does this PR do?

Add response format for agents structured output.

• [ ] Using structured output for agents (interior_design app as an example) (#issue) https://github.com/meta-llama/llama-stack-apps/issues/122

Test Plan

E2E test plan with llama-stack-apps interior_design

Please describe: Test ran:

• provide instructions so it can be reproduced. Start your distro: llama stack run llama_stack/templates/fireworks/run.yaml --env FIREWORKS_API_KEY=<API_KEY>

Run api test: PYTHONPATH=. python examples/interior_design_assistant/api.py localhost 5000 examples/interior_design_assistant/resources/documents/ examples/interior_design_assistant/resources/images/fireplaces

Sources

Results: https://github.com/meta-llama/llama-stack-client-python/pull/72

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.
• [x] Read the contributor guideline, Pull Request section?
• [ ] Updated relevant documentation.
• [ ] Wrote necessary unit or integration tests.