Change a key's reach or daily limit over the API

PATCH /v1/keys/{id} (runtime.keys.update in the TypeScript SDK, runtime keys update in the CLI) changes a key's reach (agent or account) or dailyLimitMicros (null removes the limit). A key can widen only the keys it made, never past its own reach or daily limit, and returns 403 forbidden otherwise. It can narrow any key it sees, and it never changes itself. Each change is recorded in the audit log. Previously only the website could change an existing key.