feat: data import module and payment fixes

- Add import module with CSV/Excel template download and bulk import endpoints
- Support client+subscription and outstanding invoice imports with per-row error handling
- Templates include Field Guide sheet with valid plan/area names
- Add manager role to unremitted payments endpoint
- Add createdAt field to remittance history response

src/payment/payment.controller.ts

@@ -41,9 +41,10 @@ export class PaymentController {
   }
 
   @Get('unremitted')
-  @Roles('technician', 'collector')
+  @Roles('technician', 'collector', 'manager')
   async getUnremitted(@CurrentUser() user: CurrentUserPayload) {
-    return this.paymentService.getUnremittedPayments(user.tenantId, user.sub);
+    const isManager = user.roles?.some((r: string) => ['manager', 'tenant_admin', 'super_admin'].includes(r));
+    return this.paymentService.getUnremittedPayments(user.tenantId, isManager ? null : user.sub);
   }
 
   @Get('remittances')