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/app.module.ts

@@ -29,6 +29,7 @@ import { AccountingModule } from './accounting/accounting.module';
 import { PayrollModule } from './payroll/payroll.module';
 import { RoleModule } from './role/role.module';
 import { CommentModule } from './comment/comment.module';
+import { ImportModule } from './import/import.module';
 import { GlobalExceptionFilter } from './common/filters/http-exception.filter';
 import { ResponseInterceptor } from './common/interceptors/response.interceptor';
 import { PermissionsGuard } from './common/guards/permissions.guard';
@@ -71,6 +72,7 @@ import { AccessGuard } from './common/guards/access.guard';
     PayrollModule,
     RoleModule,
     CommentModule,
+    ImportModule,
   ],
   providers: [
     { provide: APP_FILTER, useClass: GlobalExceptionFilter },