feat(api): migrate Eval API to FastAPI router (#4345)

[r-bit-rry]

Migrates the Eval API from @webmethod decorators to FastAPI routers, following the pattern established by Batches (#4191) and Benchmarks (#4309) migrations.

Changes

• New module structure: src/llama_stack_api/eval/ with api.py, models.py, fastapi_routes.py
• Removed: Old src/llama_stack_api/eval.py with @webmethod decorators
• Updated: Provider implementations to use request models

Migrated Endpoints

Method	Route
POST	/eval/benchmarks/{benchmark_id}/jobs
POST	/eval/benchmarks/{benchmark_id}/evaluations
GET	/eval/benchmarks/{benchmark_id}/jobs/{job_id}
DELETE	/eval/benchmarks/{benchmark_id}/jobs/{job_id}
GET	/eval/benchmarks/{benchmark_id}/jobs/{job_id}/result

Testing

• All pre-commit hooks pass
• OpenAPI specs regenerated
• Type checking verified

Closes #4345

[github-actions]

✱ Stainless preview builds

This PR will update the llama-stack-client SDKs with the following commit message.

feat(api): migrate Eval API to FastAPI router (#4345)

Edit this comment to update it. It will appear in the SDK's changelogs.

✅ llama-stack-client-node studio · code · diff

Your SDK built successfully.
generate ⚠️ → build ✅ → lint ✅ → test ✅

npm install https://pkg.stainless.com/s/llama-stack-client-node/4ee47718f8dd8e33d28764f47f5b807592103570/dist.tar.gz

❗ llama-stack-client-kotlin studio

Code was not generated because there was a fatal error.

✅ llama-stack-client-python studio · code · diff

Your SDK built successfully.
generate ⚠️ → build ✅ → lint ✅ → test ✅

pip install https://pkg.stainless.com/s/llama-stack-client-python/1f0211f983f81240a852ca63864849c34c13f3ca/llama_stack_client-0.4.0a14-py3-none-any.whl

✅ llama-stack-client-go studio · code · diff

Your SDK built successfully.
generate ❗ → lint ❗ → test ❗

go get github.com/stainless-sdks/llama-stack-client-go@6a76d978255f647b600fc0ceb7f4897ba4717416

⏳ These are partial results; builds are still running.

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Last updated: 2025-12-23 10:33:24 UTC

[mergify]

This pull request has merge conflicts that must be resolved before it can be merged. @r-bit-rry please rebase it. https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[r-bit-rry]

Note to reviewers, I wanted to use the Annotated for the entire request but the create_path_dependency function only works with single-field models, JobStatusRequest, JobCancelRequest, and JobResultRequest each have two path parameters (benchmark_id and job_id).

[r-bit-rry]

@leseb Continuing on our effort here

[mergify]

This pull request has merge conflicts that must be resolved before it can be merged. @r-bit-rry please rebase it. https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork