Support Codegrep models through System One

[mahesh-bespoke]

Summary

Support client.system_one(state=..., questions=..., model="nimble-codegrep-medium") as the primary Codegrep API. The low, medium, and high model aliases use the existing System One route, API key, request options, and sync/async clients, including raw and streaming response access.

Return SystemOneResponse with typed per-question raw scores, overflow/escalation details, usage, and fallback status. Existing general System One responses default to empty details and no fallback. CodegrepResponse is an alias for the shared response type.

Validate Codegrep's 1–128 noul/boolean questions and response scores without coercion. Document model selection, the shared 1 MiB request limit, and input rates of $0.02 / $0.04 / $0.12 per million tokens, with output free.

Validation

• 297 SDK regression tests pass with both Pydantic 1 and Pydantic 2.
• Full Pyright, Mypy, Ruff, formatting, and diff checks pass.
• Tests cover all model aliases, both clients, normal/raw/streaming access, explicit IDs, overrides, fallback, overflow, invalid responses, retries, and existing APIs.

Release dependency

Draft until the API gateway supports the Codegrep model aliases and is smoke-tested. No SDK version bump or PyPI publication is included.