feat(runs): add durable external-event wait diagnostics

[ccarvalho-eng]

Outcome

Operators can see why a workflow is waiting for an external event, when its timeout becomes eligible, and how the wait was resolved.

Scope

• Show active wait details including event name, correlation key, due time, timeout target, and current resolution state.
• Use Jizoku.inspect_run/2, Jizoku.inspect_run_graph/2, and Jizoku.explain_run/2 as the authoritative sources for wait and timeout diagnostics.
• Distinguish event delivery, timeout resolution, cancellation, and stale duplicate delivery without presenting resolved timeouts as active work.
• Add example-app scenarios for event arrival before timeout and timeout winning the race.

Acceptance criteria

• Run detail and graph views clearly identify active external-event waits and their timeout path.
• Resolution history records whether the event or timeout won, with no duplicate active wait after resolution.
• Explain output gives an actionable reason when delivery is rejected as stale, duplicate, or terminal.
• LiveView and example-app tests cover both event-arrival and timeout outcomes.

Runtime support: agentjido/jizoku#484 and agentjido/jizoku#508.