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/leads/application/commands/update-lead-status/update-lead-status.command.ts

@@ -0,0 +1,7 @@
+export class UpdateLeadStatusCommand {
+  constructor(
+    public readonly leadId: string,
+    public readonly agentUserId: string,
+    public readonly newStatus: string,
+  ) {}
+}

apps/api/src/modules/leads/application/commands/update-lead-status/update-lead-status.handler.ts

@@ -0,0 +1,48 @@
+import { Inject, Logger } from '@nestjs/common';
+import { CommandHandler, type EventBus, type ICommandHandler } from '@nestjs/cqrs';
+import { ForbiddenException, NotFoundException, type PrismaService } from '@modules/shared';
+import { type LeadStatus } from '../../../domain/entities/lead.entity';
+import { LEAD_REPOSITORY, type ILeadRepository } from '../../../domain/repositories/lead.repository';
+import { UpdateLeadStatusCommand } from './update-lead-status.command';
+
+@CommandHandler(UpdateLeadStatusCommand)
+export class UpdateLeadStatusHandler implements ICommandHandler<UpdateLeadStatusCommand> {
+  private readonly logger = new Logger(UpdateLeadStatusHandler.name);
+
+  constructor(
+    @Inject(LEAD_REPOSITORY) private readonly leadRepo: ILeadRepository,
+    private readonly eventBus: EventBus,
+    private readonly prisma: PrismaService,
+  ) {}
+
+  async execute(command: UpdateLeadStatusCommand): Promise<void> {
+    // Look up agent by userId
+    const agent = await this.prisma.agent.findUnique({
+      where: { userId: command.agentUserId },
+    });
+    if (!agent) {
+      throw new NotFoundException('Agent', command.agentUserId);
+    }
+
+    const lead = await this.leadRepo.findById(command.leadId);
+    if (!lead) {
+      throw new NotFoundException('Lead', command.leadId);
+    }
+
+    // Verify agent ownership
+    if (lead.agentId !== agent.id) {
+      throw new ForbiddenException('Bạn chỉ có thể cập nhật lead của chính mình');
+    }
+
+    lead.updateStatus(command.newStatus as LeadStatus);
+    await this.leadRepo.update(lead);
+
+    // Publish domain events
+    const events = lead.clearDomainEvents();
+    for (const event of events) {
+      this.eventBus.publish(event);
+    }
+
+    this.logger.log(`Lead ${command.leadId} status updated to ${command.newStatus} by agent ${agent.id}`);
+  }
+}