I2.2 — Implement IEventBus/handler host on Wolverine

[nickna]

Phase 2 · Size L · Risk: high

Scope

• Wolverine-backed IEventBus (publish + cascading).
• Handler host adapting IEventHandler<T> to Wolverine handlers; routing/listening endpoints.

Acceptance criteria

• All event types publish/consume via Wolverine in a dev run; parity tests pass.

Dependencies

I2.1.

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Part of #909 — Messaging Migration epic.