Introduce caching in CustomerRepository and refactor API integration

- Add in-memory caching for customer data in `CustomerRepository` to reduce API calls.
- Replace direct API calls with methods from `CustomerRepository`.
- Update customer-related pages (`[id]/page.tsx`, `customers/page.tsx`) to use `CustomerRepository` for data fetching.
- Adjust breadcrumb resolver to leverage `CustomerRepository`.
- Remove `axios` dependency from customer-related components.

internal_frontend/app/customers/[id]/page.tsx

@@ -1,19 +1,17 @@
 "use client";
 
-import React, {useEffect, useState, useMemo} from "react";
+import React, {useEffect, useState} from "react";
 import {useParams, useRouter} from "next/navigation";
 import {ChevronLeft} from "lucide-react";
-import axios, {AxiosError} from "axios";
 import {Button} from "@/components/ui/button";
 import {Dialog} from "@/components/ui/dialog";
 import {Skeleton} from "@/components/ui/skeleton";
 import CustomerDetailContent from "@/components/customers/details/CustomerDetailContent";
-import {Customer} from "@/services/customers/entities/customer";
 import CustomerInformationContent from "@/components/customers/details/sub/ContactInformationContent";
 import CustomerPhoneNumberContent from "@/components/customers/details/sub/CustomerPhoneNumberContent";
 import CustomerNotesContent from "@/components/customers/details/sub/CustomerNotesContent";
-
-const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || '/api';
+import {Customer} from "@/services/customers/entities/customer";
+import {CustomerRepository} from "@/services/customers/repositories/customerRepository";
 
 export default function CustomerDetailPage() {
     const router = useRouter();
@@ -35,23 +33,22 @@ export default function CustomerDetailPage() {
         setLoading(true);
         setError(null);
 
-        axios
-            .get<Customer>(`${API_BASE_URL}/customers/${id}`)
-            .then((res) => {
-                if (isMounted) {
-                    setCustomer(res.data);
+        CustomerRepository.getById(id)
+            .then((result) => {
+                if (!isMounted) return;
+
+                if (!result) {
+                    setError("Kunde nicht gefunden");
+                    setCustomer(null);
+                } else {
+                    setCustomer(result);
                 }
             })
-            .catch((error: AxiosError) => {
-                if (isMounted) {
-                    console.error('Error fetching customer:', error);
-                    setCustomer(null);
-                    setError(
-                        error.response?.status === 404
-                            ? "Kunde nicht gefunden"
-                            : "Fehler beim Laden der Kundendaten"
-                    );
-                }
+            .catch((error) => {
+                if (!isMounted) return;
+                console.error('Error fetching customer:', error);
+                setCustomer(null);
+                setError("Fehler beim Laden der Kundendaten");
             })
             .finally(() => {
                 if (isMounted) {
@@ -85,14 +82,14 @@ export default function CustomerDetailPage() {
         }
     };
 
-    const customerMetadata = useMemo(() => ({
+    const customerMetadata = {
         createdInfo: customer
             ? `Erstellt von ${customer.createdBy || "-"} am ${formatDate(customer.createdAt)}`
             : "Erstellt von - am -",
         lastActivityInfo: customer
             ? `Letzte Aktivität: ${customer.updatedBy || "-"} am ${formatDate(customer.updatedAt)}`
             : "Letzte Aktivität: - am -"
-    }), [customer]);
+    };
 
     const renderMetadata = () => {
         if (loading) {