Function build_reschedule_commands 

pub(crate) fn build_reschedule_commands(
    render_result: FragmentRenderMap,
    context: RescheduleContext,
    all_prev_fragments: HashMap<FragmentId, &InflightFragmentInfo>,
) -> MetaResult<HashMap<DatabaseId, ReschedulePlan>>

Build executable reschedule plans from the rendered fragment layout.

Callers are expected to run the no-op layout check before invoking this function so command construction stays focused on plan materialization.