feat(api): add inquiries, leads, and agents modules for Agent Portal

Build three new DDD modules following existing CQRS patterns:
- Inquiries: CRUD endpoints for buyer consultation requests with agent notification support
- Leads: Full lead lifecycle management with status state machine and conversion tracking
- Agents: Quality score calculation (event-driven on review changes) and dashboard stats API

All modules include unit tests (14 test files, all 797 tests pass).

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/inquiries/domain/events/inquiry-created.event.ts

@@ -0,0 +1,12 @@
+import { type DomainEvent } from '@modules/shared';
+
+export class InquiryCreatedEvent implements DomainEvent {
+  readonly eventName = 'inquiry.created';
+  readonly occurredAt = new Date();
+
+  constructor(
+    public readonly aggregateId: string,
+    public readonly listingId: string,
+    public readonly userId: string,
+  ) {}
+}

apps/api/src/modules/inquiries/domain/events/inquiry-read.event.ts

@@ -0,0 +1,12 @@
+import { type DomainEvent } from '@modules/shared';
+
+export class InquiryReadEvent implements DomainEvent {
+  readonly eventName = 'inquiry.read';
+  readonly occurredAt = new Date();
+
+  constructor(
+    public readonly aggregateId: string,
+    public readonly listingId: string,
+    public readonly userId: string,
+  ) {}
+}