feat(orders): credit each order to the expert who placed it, as legacy did

Legacy fixed `orders.reagent_id` once, when the order was placed, and its
«میزان فروش» summed `customer_id = X OR reagent_id = X`. The app credited
orders to the customer's CURRENT referrer and left out an expert's own
orders, so 9 of 49 imported experts showed a different figure.

- Order.salesAgentId (+ referrerCustomerId for 17 legacy orders whose
  referrer was not an expert); additive migration, recent app orders
  backfilled from the customer's referrer
- createOrder records the expert at placement time
- one shared filter (agent-orders.ts) for the experts list, expert
  detail, dashboard and the expert app; child orders follow salesAgentId
- customer page gets its «میزان فروش» back
- import carries orders.reagent_id as is; ex-experts kept as admins keep
  their profile so their own orders stay linked
- reconcile-sales: 1,557 of 1,558 match legacy's own formula; balances
  unchanged

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/src/modules/admin-dashboard/admin-dashboard.service.ts

@@ -1,6 +1,7 @@
 import { Injectable } from '@nestjs/common';
 import { OrderStatus, Prisma } from '@prisma/client';
 import { PrismaService } from '../../prisma/prisma.service';
+import { agentSalesWhere } from '../sales-agent/agent-orders';
 
 /**
  * Dashboards — legacy views/DashboardECommerce.vue (`GET get-analytics`) and
@@ -217,7 +218,7 @@ export class AdminDashboardService {
           where: {
             AND: [
               AdminDashboardService.SOLD,
-              { customer: { referredByAgentId: a.id } },
+              agentSalesWhere(a.id),
               { createdAt: { gte: since30 } },
             ],
           },