feat(iios): projection-cursor ledger + ProjectionCursorService (P9)

Adds the doc-mandated IiosProjectionCursor (ordered high-water-mark +
rolling checksum per projection/topic/partition) and a reusable
ProjectionCursorService.advance(). The checksum is a deterministic fold over
the ordered event stream, so replaying the same events reproduces it — the
KG-06 proof that replay reproduces projection outcomes.

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

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

@@ -4,6 +4,7 @@ import { PlatformModule } from './platform/platform.module';
 import { IdentityModule } from './identity/identity.module';
 import { InteractionsModule } from './interactions/interactions.module';
 import { IdempotencyModule } from './idempotency/idempotency.module';
+import { ProjectionModule } from './projection/projection.module';
 import { OutboxModule } from './outbox/outbox.module';
 import { ThreadsModule } from './threads/threads.module';
 import { MessageModule } from './messaging/message.module';
@@ -25,6 +26,7 @@ import { DevController } from './dev/dev.controller';
     IdentityModule,
     InteractionsModule,
     IdempotencyModule,
+    ProjectionModule,
     OutboxModule,
     ThreadsModule,
     MessageModule,