Design Point Started
data class DesignPointStarted(val pointId: Int, val index: Int, val totalDesignPoints: Int, val startTime: Instant) : RunEvent(source)
Emitted by ParallelDesignedExperiment immediately before each design-point coroutine begins its model build + run. Lets consumers track per-design-point state (PENDING → RUNNING) before the corresponding DesignPointCompleted event arrives.