Standalone Activities: Durable job processing, now in Public Preview

This post announces the Public Preview of Standalone Activities, a feature that allows Temporal Activities to run independently of Workflows. It details how to invoke them directly from a client using `client.execute_activity`, highlighting their durable persistence, retry capabilities, and visibility in the Temporal Web UI. The post contrasts this with traditional job queue systems, emphasizing benefits like default durability, full visibility via stable IDs, and the ability to seamlessly transition to Workflows. It lists supported SDKs and core capabilities, with future GA features mentioned. Getting started guides for various SDKs are provided.