feat: add profile route and sidebar navigation; implement inventory and view product pages

- Added a new profile route under the hidden layout.
- Introduced a Sidebar component for navigation between inventory, add product, and profile pages.
- Created InventoryPage to display a list of products with sorting and pagination.
- Implemented ViewProduct page to show details of a selected product.
- Integrated API calls for fetching products and product details.
- Updated route tree to include new routes and components.

frontend/src/routes/app/_hiddenLayout.tsx

@@ -1,5 +1,5 @@
-// routes/app/_layout.tsx (oder app.tsx als Parent)
 import { Outlet, createFileRoute } from "@tanstack/react-router";
+import { Sidebar } from "../../components/Sidebar";
 
 export const Route = createFileRoute("/app/_hiddenLayout")({
   component: AppLayout,
@@ -7,9 +7,11 @@ export const Route = createFileRoute("/app/_hiddenLayout")({
 
 function AppLayout() {
   return (
-    <div>
-      <h1>Layout</h1>
-      <Outlet />
+    <div className="flex min-h-screen w-full bg-[#f7f9fc]">
+      <Sidebar />
+      <main className="flex-1 px-8 py-6">
+        <Outlet />
+      </main>
     </div>
   );
 }

frontend/src/routes/app/_hiddenLayout/inventory.tsx

@@ -1,5 +1,6 @@
 import { createFileRoute, redirect } from "@tanstack/react-router";
 import { isAuthenticated } from "../../../utils/auth";
+import { InventoryPage } from "../../../pages/Inventory";
 
 export const Route = createFileRoute("/app/_hiddenLayout/inventory")({
   beforeLoad: async () => {
@@ -13,9 +14,5 @@ export const Route = createFileRoute("/app/_hiddenLayout/inventory")({
 });
 
 function RouteComponent() {
-  return (
-    <>
-      <p>Inventar</p>
-    </>
-  );
+  return <InventoryPage />;
 }

frontend/src/routes/app/_hiddenLayout/profile.tsx

@@ -0,0 +1,9 @@
+import { createFileRoute } from '@tanstack/react-router'
+
+export const Route = createFileRoute('/app/_hiddenLayout/profile')({
+  component: RouteComponent,
+})
+
+function RouteComponent() {
+  return <div>Hello "/app/_hiddenLayout/profile"!</div>
+}

frontend/src/routes/app/_hiddenLayout/view-product.tsx

@@ -1,5 +1,7 @@
 import { createFileRoute, redirect } from "@tanstack/react-router";
+import { z } from "zod";
 import { isAuthenticated } from "../../../utils/auth";
+import { ViewProduct } from "../../../pages/ViewProduct";
 
 export const Route = createFileRoute("/app/_hiddenLayout/view-product")({
   beforeLoad: async () => {
@@ -9,9 +11,13 @@ export const Route = createFileRoute("/app/_hiddenLayout/view-product")({
       });
     }
   },
+  validateSearch: z.object({
+    product: z.string(),
+  }),
   component: RouteComponent,
 });
 
 function RouteComponent() {
-  return <div>Hello "/app/view-product"!</div>;
+  const { product } = Route.useSearch();
+  return <ViewProduct uuid={product} />;
 }