Schedules a sync (the connection between a service and a destination, identified by syncId) to run immediately. Returns the new taskId plus status and logs URLs to poll. If a task is already running, the call fails and returns runningTask pointing at the in-flight job. Pass fullSync=true to drop the saved cursor and re-sync from scratch.

Auth: bearer token (<keyId>:<secret>). Internal scheduler calls authenticate with the sync-controller key instead.