## What changed
- Recognize `misalignment_policy_violation` errors from response streams and HTTP 400 or 403 responses.
- Preserve the upstream message, use a fallback for blank messages, and treat the error as non-retryable.
- Expose `misalignmentPolicyViolation` through the app-server protocol and generated schemas so turns fail with a typed terminal error.
## Testing
- Cover streamed and HTTP policy violations, fallback messages, retry behavior, and app-server turn completion.
GitOrigin-RevId: fd3485bf0be7bfe3d51c078bbc36a081692fd57f