Expand description
Parallel operation — fan-out with completion criteria.
Implement FR19-FR22: concurrent branches, completion criteria, independent checkpoint namespaces, tokio::spawn with Send + ’static.
The parallel operation uses OperationType::Context on the wire with
sub_type “Parallel” for the outer block and “ParallelBranch” for each
branch. Each branch gets its own child DurableContext with an isolated
operation ID namespace.