pub async fn start_preview(camera_id: String)Expand description
Async helper: kick off start_preview for the given camera id.
Failures are silently swallowed today — the M-CAM.3 frame channel
hasn’t landed yet, so observable behaviour is “state machine
transitions to Running”. Once frames flow the Recorder
<CameraPreview /> overlay will reflect any error via the
RecorderPreviewState enum.