recording_stopped events — test recording with annotated
video and structured test results.
Discriminated by the required video_path field: only recording_stopped
events carry cognition.ai/videoPath. video_path is a non-Option
String with no #[serde(default)], so serde’s untagged enum dispatch
will only pick this variant when the incoming _meta actually has
cognition.ai/videoPath. Mirrors the pattern used by ReportBlockerMeta,
CognitionMcpToolMeta, and CognitionPermissionRequestMeta.