[Submission] Temporal workflow demo: run multiple activity "providers" in parallel, return the first success, and cancel the rest using CancellationScope—clear pattern for multi-path latency and resilience without serial retry chains.

[Submission] Temporal workflow demo: run multiple activity "providers" in parallel, return the first success, and cancel the rest using CancellationScope—clear pattern for multi-path latency and resilience without serial retry chains. #66