fix(profiles): make public profiles accessible without authentication and unify 404 behavior

Backend changes:
- Removed authentication requirement from GET /api/users/:username endpoint
- Removed authentication requirement from GET /api/users/:username/ratings endpoint
- These are public profile endpoints and should be accessible to all users

Frontend changes:
- PublicProfilePage now shows NotFoundPage component when user doesn't exist
- Unified 404 behavior: both invalid URLs and non-existent users show the same 404 page
- NotFoundPage "Requested URL" box now only shows in dev mode (import.meta.env.DEV)
- Removed unused AlertCircle icon import from PublicProfilePage

backend/src/routes/users.js

@@ -82,7 +82,7 @@ router.patch('/me', authenticate, updateProfileValidation, updateProfile);
 router.patch('/me/password', authenticate, changePasswordValidation, changePassword);
 
 // GET /api/users/:username - Get public user profile by username
-router.get('/:username', authenticate, async (req, res, next) => {
+router.get('/:username', async (req, res, next) => {
   try {
     const { username } = req.params;
 
@@ -149,7 +149,7 @@ router.get('/:username', authenticate, async (req, res, next) => {
 });
 
 // GET /api/users/:username/ratings - Get ratings for a user
-router.get('/:username/ratings', authenticate, async (req, res, next) => {
+router.get('/:username/ratings', async (req, res, next) => {
   try {
     const { username } = req.params;
 

frontend/src/pages/NotFoundPage.jsx

@@ -45,7 +45,8 @@ export default function NotFoundPage() {
             </p>
           </div>
 
-          {/* Current Path */}
+          {/* Current Path - Only show in dev mode */}
+          {import.meta.env.DEV && (
             <div className="mb-8 p-4 bg-gray-100 rounded-lg">
               <p className="text-sm text-gray-500 mb-1">Requested URL:</p>
               <code className="text-sm text-gray-800 break-all">
@@ -53,6 +54,7 @@ export default function NotFoundPage() {
                 {location.search}
               </code>
             </div>
+          )}
 
           {/* Action Buttons */}
           <div className="flex flex-col sm:flex-row gap-3 justify-center">

frontend/src/pages/PublicProfilePage.jsx

@@ -2,8 +2,9 @@ import { useState, useEffect } from 'react';
 import { useParams, Link } from 'react-router-dom';
 import { authAPI, ratingsAPI } from '../services/api';
 import Layout from '../components/layout/Layout';
-import { User, MapPin, Globe, Hash, Youtube, Instagram, Facebook, Award, Users, Star, Calendar, Loader2, AlertCircle, ThumbsUp } from 'lucide-react';
+import { User, MapPin, Globe, Hash, Youtube, Instagram, Facebook, Award, Users, Star, Calendar, Loader2, ThumbsUp } from 'lucide-react';
 import Avatar from '../components/common/Avatar';
+import NotFoundPage from './NotFoundPage';
 
 const PublicProfilePage = () => {
   const { username: rawUsername } = useParams();
@@ -61,25 +62,7 @@ const PublicProfilePage = () => {
   }
 
   if (error) {
-    return (
-      <Layout>
-        <div className="min-h-screen bg-gray-50 flex items-center justify-center">
-          <div className="max-w-md w-full mx-4">
-            <div className="bg-white rounded-lg shadow-sm p-8 text-center">
-              <AlertCircle className="w-16 h-16 text-red-500 mx-auto mb-4" />
-              <h2 className="text-2xl font-bold text-gray-900 mb-2">User Not Found</h2>
-              <p className="text-gray-600 mb-6">{error}</p>
-              <Link
-                to="/events"
-                className="inline-block px-6 py-2 bg-primary-600 text-white rounded-md hover:bg-primary-700"
-              >
-                Back to Events
-              </Link>
-            </div>
-          </div>
-        </div>
-      </Layout>
-    );
+    return <NotFoundPage />;
   }
 
   return (