Added achievement data

app/Http/Controllers/AchievementController.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace App\Http\Controllers;
+
+use App\Models\Achievement;
+use App\Models\User;
+use Illuminate\Http\Request;
+use Inertia\Inertia;
+
+class AchievementController extends Controller
+{
+    public function index(User $user)
+    {
+        $achievements = Achievement::with(['category', 'difficulty'])
+            ->get()
+            ->groupBy(fn(Achievement $a) => $a->category->name)
+            ->map(fn($group) => $group->sortBy('id')->values());
+
+        $userAchievements = $user->achievements()
+            ->with('achievement')
+            ->orderBy('achievement_id')
+            ->get()
+            ->keyBy('achievement_id');
+
+        return Inertia::render('UserAchievements', [
+            'user'             => $user,
+            'canEdit'          => auth()->id() === $user->id,
+            'isFollowing'      => auth()->check() && auth()->user()->isFollowing($user),
+            'achievements'     => $achievements,
+            'userAchievements' => $userAchievements,
+        ]);
+    }
+}