feat(iios): idempotency ledger on outbound egress (409 on key reuse) (P9)

OutboundService.send is now opt-in idempotent: an explicit idempotencyKey routes
the send through IdempotencyService.run (Slice 6), so reusing a key with a
different target/payload returns a 409 conflict and a same-key/same-request retry
replays the cached command. The inner findUnique early-return stays as a backstop
so a FAILED-then-retried send never collides on the command's unique key. Keyless
sends keep the old behavior (no ledger row).

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

packages/iios-service/src/isolation.spec.ts

@@ -12,6 +12,7 @@ import { AiJobService } from './ai/ai.service';
 import { AiBudgetGuard } from './ai/ai-budget.guard';
 import { CalendarService } from './calendar/calendar.service';
 import { OutboundService } from './adapters/outbound.service';
+import { IdempotencyService } from './idempotency/idempotency.service';
 import { CapabilityBroker } from './capability/capability.broker';
 import { CapabilityProviderRegistry } from './capability/capability.registry';
 import type { PrismaService } from './prisma/prisma.service';
@@ -27,7 +28,7 @@ const B: MessagePrincipal = { userId: 'b1', orgId: 'org_B', appId: 'portal-demo'
 const START = '2026-07-02T10:00:00.000Z';
 
 const ai = () => new AiJobService(asService, makeFakePorts(), makeFakeInference(), new AiBudgetGuard(asService), actors);
-const outbound = () => new OutboundService(asService, new CapabilityBroker(makeFakePorts(), new CapabilityProviderRegistry()));
+const outbound = () => new OutboundService(asService, new CapabilityBroker(makeFakePorts(), new CapabilityProviderRegistry()), new IdempotencyService(asService));
 const routeSvc = () => new RouteService(asService, new RouteSimulator(asService, new RuleEngine()), outbound(), actors);
 const cal = () => new CalendarService(asService, makeFakePorts(), actors, ai(), outbound());