Refactor navigation structure and API routes

- Centralize user menu, sidebar items, and breadcrumb logic.
- Map consistent API endpoints in `customerRoutes`.
- Replace inline route definitions with reusable constants.
- Refactor auth configuration file location.
- Improve `<Link>` usage to replace static `<a>` elements.
- Adjust sidebar and dropdown components to use dynamic navigation configurations.

internal_frontend/app/api/auth/[...nextauth]/route.ts

@@ -1,5 +1,5 @@
 import NextAuth from "next-auth";
-import {authOptions} from "@/lib/auth/authOptions";
+import {authOptions} from "@/lib/api/auth/authOptions";
 
 const handler = NextAuth(authOptions);
 export {handler as GET, handler as POST};

internal_frontend/app/api/customers/[id]/route.ts

@@ -1,9 +1,10 @@
 import {NextRequest, NextResponse} from "next/server";
 import {serverCall} from "@/lib/api/serverCall";
+import {customerRoutes} from "@/app/api/customers/customerRoutes";
 
 export async function GET(request: NextRequest) {
     const id = request.url.split('/').pop();
-    const response = await serverCall(`/customers/${id}`, "GET");
+    const response = await serverCall(customerRoutes.getById(id!), "GET");
 
     if (!response.ok) {
         return NextResponse.json({error: "Customer not found"}, {status: 404});

internal_frontend/app/api/customers/customerRoutes.ts

@@ -1,4 +1,5 @@
 export const customerRoutes = {
     create: "/customers",
     validate: "/customers/validate",
+    getById: (id: string) => `/customers/${id}`,
 };

internal_frontend/app/api/customers/route.ts

@@ -1,14 +1,15 @@
 import {NextRequest, NextResponse} from "next/server";
 import {serverCall} from "@/lib/api/serverCall";
+import {customerRoutes} from "@/app/api/customers/customerRoutes";
 
 export async function GET() {
-    const data = await serverCall("/customers", "GET");
+    const data = await serverCall(customerRoutes.create, "GET");
     const customers = await data.json();
     return NextResponse.json(customers);
 }
 
 export async function POST(req: NextRequest) {
     const body = await req.json()
-    const result = await serverCall("/customers", "POST", body);
+    const result = await serverCall(customerRoutes.create, "POST", body);
     return NextResponse.json(result.json());
 }

internal_frontend/app/customers/page.tsx

@@ -1,7 +1,6 @@
 "use client";
 
 import {useState, useEffect, useMemo} from "react";
-import {useRouter} from "next/navigation";
 import {Button} from "@/components/ui/button";
 import {Input} from "@/components/ui/input";
 import {Card, CardContent} from "@/components/ui/card";
@@ -25,9 +24,9 @@ import {ArrowRight} from "lucide-react";
 import {NewCustomerModal} from "@/components/customers/modal/NewCustomerModal";
 import axios from "axios";
 import {Customer} from "@/services/customers/entities/customer";
+import Link from "next/link";
 
 export default function CustomersPage() {
-    const router = useRouter();
     const [customers, setCustomers] = useState<Customer[]>([]);
     const [search, setSearch] = useState("");
     const [loading, setLoading] = useState(true);
@@ -50,7 +49,7 @@ export default function CustomersPage() {
     }, []);
 
     const filtered = useMemo(() => {
-        if(customers.length === 0) return [];
+        if (customers.length === 0) return [];
 
         return customers.filter(
             (c) =>
@@ -143,13 +142,11 @@ export default function CustomersPage() {
                                                 <TableCell>{customer.city}</TableCell>
                                                 <TableCell>{new Date(customer.createdAt).toLocaleString()}</TableCell>
                                                 <TableCell>
-                                                    <Button
-                                                        variant="ghost"
-                                                        size="icon"
-                                                        onClick={() => router.push(`/customers/${customer.id}`)}
-                                                    >
-                                                        <ArrowRight className="w-4 h-4"/>
-                                                    </Button>
+                                                    <Link href={`/customers/${customer.id}`}>
+                                                        <Button variant="ghost" size="icon">
+                                                            <ArrowRight className="w-4 h-4"/>
+                                                        </Button>
+                                                    </Link>
                                                 </TableCell>
                                             </TableRow>
                                         ))}

internal_frontend/app/layout.tsx

@@ -8,7 +8,7 @@ import {Separator} from "@/components/ui/separator";
 import {DynamicBreadcrumb} from "@/components/dynamic-breadcrumb";
 import {getServerSession} from "next-auth";
 import LoginScreen from "@/components/login-screen";
-import {authOptions} from "@/lib/auth/authOptions";
+import {authOptions} from "@/lib/api/auth/authOptions";
 
 export const metadata: Metadata = {
     title: "Internal | Rhein Software",