feat: add rent payment schedules and receipts

frontend/src/app/services/rent-payment.service.ts

@@ -0,0 +1,34 @@
+import { HttpClient } from '@angular/common/http';
+import { Injectable, inject } from '@angular/core';
+import { Observable } from 'rxjs';
+
+export type RentPaymentStatus = 'PAID' | 'LATE' | 'UPCOMING';
+
+export interface RentPayment {
+  id: string;
+  leaseId: string;
+  month: string;
+  dueDate: string;
+  rent: number;
+  charges: number;
+  total: number;
+  status: RentPaymentStatus;
+  paidAt: string | null;
+}
+
+@Injectable({ providedIn: 'root' })
+export class RentPaymentService {
+  private readonly http = inject(HttpClient);
+
+  getRentPayments(): Observable<RentPayment[]> {
+    return this.http.get<RentPayment[]>('/api/rent-payments');
+  }
+
+  markPaid(id: string): Observable<RentPayment> {
+    return this.http.put<RentPayment>(`/api/rent-payments/${id}/paid`, {});
+  }
+
+  downloadReceipt(id: string): Observable<Blob> {
+    return this.http.get(`/api/rent-payments/${id}/receipt`, { responseType: 'blob' });
+  }
+}