CLI runtime alias treated as missing embedded agent harness

A gateway allowed model runtime policies to use CLI backend aliases such as claude-cli, but the embedded AgentHarness selector also consumed the same policy. When a turn entered an embedded/follow-up selection path, the selector interpreted claude-cli as a plugin harness id and raised MissingAgentHarnessError: Requested agent harness "claude-cli" is not registered, even though the CLI backend itself was registered and working.