migrating-world-v4-to-v5

Upgrades a custom Workflow SDK World implementation from the v4 spec to v5. Use when a package implements the World interface from @workflow/world and is moving to 5.x — event IDs that are ULIDs rather than slot positions, Event id is not slot-numbered at replay time, a specVersion the runtime refuses, writeToStream / closeStream / readFromStream as top-level World methods, steps.get or events.listByCorrelationId…