feat(iios): wire the three-proof gate into the request path (§1b)

Applies the context-attestation verifier at the request boundary via a guard, so a
stolen/forged/replayed attestation is rejected before IIOS acts — while staying safe
to roll out.

- ContextAttestationGuard: if an X-Context-Attestation header is present, verify it
  (its app_id must match the actor token's app_id) → 403 on any failure; if absent,
  allow only when IIOS_REQUIRE_ATTESTATION != 1 (dev/zero-trust), else 403. The flag is
  read per-request and defaults OFF, so existing callers keep working until AppShell/
  be-crm start forwarding attestations.
- AttestationModule (@Global): provides the verifier + Prisma stores + guard, and
  dev-seeds the crm-support-widget client so locally minted attestations verify.
- Guard applied to ThreadsController + SupportController.
- Tests (5 pass, no DB): not-required-allows, required-rejects, valid, forged, replayed.

Workload/mTLS (proof #2) stays a mesh concern. Next: SDK header passthrough + demote
be-crm IiosClient to forward an attestation, then flip the flag to prove end-to-end.

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

packages/iios-service/src/platform/attestation.module.ts

@@ -0,0 +1,44 @@
+import { Global, Module, type OnModuleInit } from '@nestjs/common';
+import { PrismaService } from '../prisma/prisma.service';
+import { ContextAttestationVerifier } from './context-attestation';
+import { PrismaClientRegistry, PrismaNonceStore } from './attestation-stores';
+import { ContextAttestationGuard } from './context-attestation.guard';
+
+/**
+ * Wires the context-attestation trust layer into DI and exposes the guard globally so any
+ * controller can enforce the three-proof gate. Also dev-seeds a registered client so locally
+ * minted attestations verify (prod registers clients out-of-band).
+ */
+@Global()
+@Module({
+  providers: [
+    PrismaClientRegistry,
+    PrismaNonceStore,
+    {
+      provide: ContextAttestationVerifier,
+      useFactory: (reg: PrismaClientRegistry, nonces: PrismaNonceStore) =>
+        new ContextAttestationVerifier(reg, nonces, { audience: process.env.IIOS_ATTESTATION_AUDIENCE ?? 'iios-core' }),
+      inject: [PrismaClientRegistry, PrismaNonceStore],
+    },
+    ContextAttestationGuard,
+  ],
+  exports: [ContextAttestationVerifier, ContextAttestationGuard],
+})
+export class AttestationModule implements OnModuleInit {
+  constructor(private readonly prisma: PrismaService) {}
+
+  /** Dev seed: register the CRM support client so an attestation signed with the shared dev
+   *  secret verifies locally. Gated by IIOS_DEV_TOKENS + IIOS_ATTESTATION_DEV_SECRET; best-effort. */
+  async onModuleInit(): Promise<void> {
+    if (process.env.IIOS_DEV_TOKENS !== '1') return;
+    const secret = process.env.IIOS_ATTESTATION_DEV_SECRET;
+    if (!secret) return;
+    await this.prisma.iiosClientRegistry
+      .upsert({
+        where: { clientId: 'crm-support-widget' },
+        create: { clientId: 'crm-support-widget', clientType: 'SUPPORT_BFF', allowedAppIds: ['crm-web'], attestSecret: secret, status: 'ACTIVE' },
+        update: { attestSecret: secret, allowedAppIds: ['crm-web'], status: 'ACTIVE' },
+      })
+      .catch(() => undefined);
+  }
+}