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/services/user.service.ts

@@ -0,0 +1,19 @@
+import api from "@/lib/api";
+import type { User, UserProfile } from "@/types/user";
+
+export const UserService = {
+  async getMe(): Promise<User> {
+    const { data } = await api.get<User>("/users/me");
+    return data;
+  },
+
+  async getProfile(username: string): Promise<User> {
+    const { data } = await api.get<User>(`/users/public/${username}`);
+    return data;
+  },
+
+  async updateMe(update: Partial<User>): Promise<User> {
+    const { data } = await api.patch<User>("/users/me", update);
+    return data;
+  },
+};