Cloud project previews wake up much faster

Cloud project previews now come back much faster after they have gone idle.

For projects with a warm snapshot available, Preview can wake in about 1-2 seconds instead of waiting for a full cold start that can take about a minute. That is up to around 60x faster when you return to a recent Cloud project.

This is most visible when you are iterating on a full-stack app: open the project, wait for Preview, make a change, leave it idle, then come back later. Playcode can now resume the working project state instead of rebuilding the whole dev environment every time.

If a project needs a clean start, for example after an infrastructure update or an expired snapshot, Playcode falls back to the slower cold start path so the project still opens correctly.