feat(mail): tag mail threads source=crm-mail (list separately from chat)

ingest() puts metadata on the interaction, not the thread, and listThreads filters
THREAD metadata — so MailService now tags the thread directly after deposit
(source=crm-mail). Lets the CRM list mail threads apart from Messenger chat
(source=crm-messenger). 7 tests. NOTE: requires an IIOS redeploy.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/iios-service/src/mail/mail.service.ts

@@ -1,4 +1,6 @@
 import { Injectable } from '@nestjs/common';
+import { Prisma } from '@prisma/client';
+import { PrismaService } from '../prisma/prisma.service';
 import { IngestService } from '../interactions/ingest.service';
 import { ActorResolver, type MessagePrincipal } from '../identity/actor.resolver';
 import { TemplateService } from '../templates/template.service';
@@ -55,8 +57,12 @@ export class MailService {
     private readonly ingest: IngestService,
     private readonly sender: TemplatedSender,
     private readonly actors: ActorResolver,
+    private readonly prisma: PrismaService,
   ) {}
 
+  /** Marks a thread as CRM mail so it lists separately from chat (Messenger uses source=crm-messenger). */
+  static readonly SOURCE = 'crm-mail';
+
   async postInternal(principal: MessagePrincipal, input: PostInternalInput): Promise<{ threadId: string; interactionId: string }> {
     const { content } = await this.templates.render(input.source, input.vars ?? {}, { channel: 'INTERNAL', ...(input.locale ? { locale: input.locale } : {}) });
     return this.deposit(principal, input.recipientUserId, content, input.idempotencyKey, 'PORTAL');
@@ -103,6 +109,13 @@ export class MailService {
     await this.actors.ensureParticipant(res.threadId, senderActor.id);
     await this.actors.ensureParticipant(res.threadId, recipientActor.id);
 
+    // Tag the thread as CRM mail (thread metadata) so it lists separately from Messenger chat.
+    // ingest() puts req.metadata on the interaction, not the thread, so we set it here directly.
+    await this.prisma.iiosThread.update({
+      where: { id: res.threadId },
+      data: { metadata: { source: MailService.SOURCE } as Prisma.InputJsonValue },
+    });
+
     return { threadId: res.threadId, interactionId: res.interactionId };
   }
 }