Refresh Video Metrics

Re-capture a tracked video's metrics via Apify right now.

The on-demand counterpart to the scheduler tick — used by the "retry" button when a capture failed (e.g. a transient Apify error or a quota limit that has since been raised). Best-effort: an Apify failure or unset token returns {"ok": False, "error": ...} instead of a 5xx, and the error is stamped on the row so the UI can keep showing it. On success the cadence anchors advance and last_error is cleared.