refactor(task): align continuation ids with task_id

src/tools/delegate-task/task-id.ts

@@ -0,0 +1,5 @@
+import type { DelegateTaskArgs } from "./types"
+
+export function getTaskID(args: Pick<DelegateTaskArgs, "task_id" | "session_id">): string | undefined {
+  return args.task_id ?? args.session_id
+}