feat: make stripe functional

frontend/src/app/service/deposit.service.ts

@@ -0,0 +1,15 @@
+import { inject, Injectable } from '@angular/core';
+import { HttpClient } from '@angular/common/http';
+import { Observable } from 'rxjs';
+
+
+@Injectable({
+  providedIn: 'root'
+})
+export class DepositService {
+  private http: HttpClient = inject(HttpClient);
+
+  handleDeposit(amount: number): Observable<{ sessionId: string }> {
+    return this.http.post<{sessionId: string}>('/backend/deposit/checkout', {amount});
+  }
+}