Feature Request: Admin API endpoint for Workspace Rate/Spend Limits

## Summary

The Admin API currently supports workspace CRUD and member management, but there is no endpoint to programmatically configure **rate limits** or **spend limits** per workspace.

These settings are only available through the Claude Console UI.

## Use Case

When managing multiple workspaces at scale (e.g., provisioning workspaces per team/project via automation), it is essential to set rate limits and spend limits programmatically. Without API support, administrators must manually configure each workspace's limits through the Console, which does not scale.

## Requested Endpoints

| Operation | Suggested Method & Path |
|-----------|------------------------|
| Get workspace limits | `GET /v1/organizations/workspaces/{workspace_id}/limits` |
| Set/Update workspace limits | `POST /v1/organizations/workspaces/{workspace_id}/limits` |

### Expected parameters (set/update)

```json
{
"rate_limits": {
"requests_per_minute": 100,
"input_tokens_per_minute": 50000,
"output_tokens_per_minute": 10000
},
"spend_limits": {
"monthly_spend_limit_usd": 500
}
}
```

## Current Workaround

Manual configuration via Claude Console (Settings > Workspaces > Limits tab).

## References

- [Admin API - Workspaces](https://platform.claude.com/docs/en/api/admin/workspaces)
- [Workspaces documentation](https://platform.claude.com/docs/en/build-with-claude/workspaces)