feat: introduce new app routes with modular structure and enhanced features

Added modular app routes including `login`, `dashboard`, `categories`, `trends`, and `upload`. Introduced reusable components such as `ContentList`, `ContentSkeleton`, and `AppSidebar` for improved UI consistency. Enhanced authentication with `AuthProvider` and implemented lazy loading, dynamic layouts, and infinite scrolling for better performance.

frontend/src/app/sitemap.ts

@@ -0,0 +1,45 @@
+import type { MetadataRoute } from "next";
+import { ContentService } from "@/services/content.service";
+import { CategoryService } from "@/services/category.service";
+
+export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
+  const baseUrl = process.env.NEXT_PUBLIC_APP_URL || "https://memegoat.local";
+
+  // Pages statiques
+  const routes = ["", "/trends", "/recent"].map((route) => ({
+    url: `${baseUrl}${route}`,
+    lastModified: new Date(),
+    changeFrequency: "daily" as const,
+    priority: route === "" ? 1 : 0.8,
+  }));
+
+  // Catégories
+  try {
+    const categories = await CategoryService.getAll();
+    const categoryRoutes = categories.map((category) => ({
+      url: `${baseUrl}/category/${category.slug}`,
+      lastModified: new Date(),
+      changeFrequency: "weekly" as const,
+      priority: 0.6,
+    }));
+    routes.push(...categoryRoutes);
+  } catch (error) {
+    console.error("Sitemap: Failed to fetch categories");
+  }
+
+  // Mèmes (limité aux 100 derniers pour éviter un sitemap trop gros d'un coup)
+  try {
+    const contents = await ContentService.getRecent(100, 0);
+    const memeRoutes = contents.data.map((meme) => ({
+      url: `${baseUrl}/meme/${meme.slug}`,
+      lastModified: new Date(meme.updatedAt),
+      changeFrequency: "monthly" as const,
+      priority: 0.5,
+    }));
+    routes.push(...memeRoutes);
+  } catch (error) {
+    console.error("Sitemap: Failed to fetch memes");
+  }
+
+  return routes;
+}