feat(p9): IiosDlqItem + DlqService (dead-letter + deterministic replay)

Task D.1: mandated dlq_item table (sourceType/sourceId/failureStage/errorCode/
retryCount/payloadRef/consumerName/scopeId/status). DlqService.record (idempotent
per consumer+sourceId, bumps retryCount), onConsumerFailure (quarantine + clear the
IiosProcessedEvent claim so it's replayable — fixes claim-then-fail), registerHandler
+ replay (clears claim, awaits the registered consumer handler → RESOLVED on success,
QUARANTINED+retry on repeat throw; outbox-sourced items reset to PENDING). Wired into
OutboxModule; resetDb truncates it. 3 tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/iios-service/src/outbox/outbox.module.ts

@@ -1,9 +1,10 @@
 import { Module } from '@nestjs/common';
 import { OutboxBus } from './outbox.bus';
 import { OutboxRelay } from './outbox.relay';
+import { DlqService } from './dlq.service';
 
 @Module({
-  providers: [OutboxBus, OutboxRelay],
-  exports: [OutboxBus, OutboxRelay],
+  providers: [OutboxBus, OutboxRelay, DlqService],
+  exports: [OutboxBus, OutboxRelay, DlqService],
 })
 export class OutboxModule {}