I2.5 — Port the test suite to Wolverine (local queues / test harness)

[nickna]

Phase 2 · Size M · Risk: med

Scope

• Dev/CI uses Wolverine in-memory local queues.
• Update the I1.8 test doubles to exercise the Wolverine backend too.

Acceptance criteria

• Suite green on the Wolverine backend in CI.

Dependencies

I2.2.

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Part of #909 — Messaging Migration epic.