embroider

Appends a DraftStage.Embroider stage referencing opId and returns a new Draft.

The embroider stage is the single coordination step — tagged CoordinationKind.Coordinated. Place it last (or let the E-2 planner defer it there automatically) to minimise consensus rounds.

Produces a path: the new node's sole predecessor is the current tip. No op is invoked. Only the name is recorded.