feat: add guardian transactions feature with response DTOs and service integration

src/guardian/services/guardian-transactions.service.ts

@@ -0,0 +1,45 @@
+import { Injectable } from '@nestjs/common';
+import { CustomerService } from '~/customer/services';
+import { GuardianHomeResponseDto, PagedTransactionsResponseDto } from '~/card/dtos/responses';
+import { TransactionItemResponseDto } from '~/card/dtos/responses';
+import { ParentTransactionType } from '~/card/enums';
+import { TransactionService } from '~/card/services/transaction.service';
+
+@Injectable()
+export class GuardianTransactionsService {
+  constructor(
+    private readonly customerService: CustomerService,
+    private readonly transactionService: TransactionService,
+  ) {}
+
+  async getHome(guardianId: string, size: number): Promise<GuardianHomeResponseDto> {
+    const parent = await this.customerService.findCustomerById(guardianId);
+    const primaryCard = parent.cards?.[0];
+
+    let availableBalance = 0;
+    if (primaryCard) {
+      const hasLimit = typeof primaryCard.limit === 'number' && !Number.isNaN(primaryCard.limit);
+      const hasBalance = primaryCard.account && typeof primaryCard.account.balance === 'number';
+      if (hasLimit && hasBalance && primaryCard.limit > 0) {
+        availableBalance = Math.min(primaryCard.limit, primaryCard.account.balance);
+      } else if (hasBalance) {
+        availableBalance = primaryCard.account.balance;
+      }
+    }
+
+    const items: TransactionItemResponseDto[] = await this.transactionService.getParentConsolidated(guardianId, 1, size);
+
+    return new GuardianHomeResponseDto(availableBalance, items);
+  }
+
+  async getTransactions(
+    guardianId: string,
+    page: number,
+    size: number,
+    type?: ParentTransactionType,
+  ): Promise<PagedTransactionsResponseDto> {
+    return this.transactionService.getParentTransactionsPaginated(guardianId, page, size, type);
+  }
+}
+
+