Function derive_task_id 

pub fn derive_task_id(flow_run_id: FlowRunId, node_id: NodeId) -> TaskId

Derives a deterministic TaskId for a step from a FlowRunId and NodeId.

Uses UUID v5 with the FlowRunId as namespace and the NodeId bytes prefixed with “task:” as name. The prefix distinguishes this derivation from derive_step_run_id to avoid collisions.