Retracted: Retract v0.1.0 through v0.1.3: v0.1.0–v0.1.2 rewrote the journal
(async RunStep + dropped seq). v0.1.3 is the last release before
typed step input and WithStepVersion. Start from v0.1.4.
Package main demonstrates the struct / method-receiver style of durable-go.
AgentRunner is a production-style struct with injected dependencies.
It implements durable.Task[AgentInput, AgentOutput] so it can be passed
directly to durable.Run – no adapter or wrapper needed.