Remove CustomerRepository and replace with direct API calls

- Remove `CustomerRepository` and its methods for customer management and caching.
- Refactor customer-related pages (`[id]/page.tsx`, `customers/page.tsx`) to use direct `fetch` API calls.
- Update breadcrumb resolver to fetch data directly from the API.
- Simplify `addCustomer` use case to avoid repository dependency.

internal_frontend/services/customers/usecases/addCustomer.ts

@@ -1,7 +1,6 @@
 "use server";
 
 import {CreateCustomerDto} from "@/services/customers/dtos/createCustomer.dto";
-import {CustomerRepository} from "@/services/customers/repositories/customerRepository";
 
 export async function addCustomer(params: CreateCustomerDto): Promise<void> {
     const {email, name, companyName, street, zip, city, phoneNumbers, notes} = params;
@@ -17,5 +16,15 @@ export async function addCustomer(params: CreateCustomerDto): Promise<void> {
         notes: notes.map(({text}) => ({text})),
     };
 
-    await CustomerRepository.create(payload);
+    const response = await fetch('/api/customers', {
+        method: 'POST',
+        headers: {
+            'Content-Type': 'application/json',
+        },
+        body: JSON.stringify(payload)
+    });
+
+    if (!response.ok) {
+        throw new Error(`Failed to create customer: ${response.statusText}`);
+    }
 }