feat: Add user level and experience attributes, and implement reward, task, and quest models with corresponding controllers and migrations

backend/app/Http/Controllers/UserController.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Http\Controllers;
+
+use App\Models\Reward;
+use Illuminate\Http\Request;
+
+class UserController extends Controller
+{
+    public function status(Request $request)
+    {
+        $user = $request->user();
+        $xpForNextLevel = $user->level * 100;
+
+        // Finde noch nicht freigeschaltete Rewards, die in Reichweite sind
+        $upcomingRewards = Reward::where('unlocked_at_level', '>', $user->level)->limit(5)->get();
+
+        return response()->json([
+            'level' => $user->level,
+            'xp' => $user->xp,
+            'xp_for_next_level' => $xpForNextLevel,
+            'upcoming_rewards' => $upcomingRewards
+        ]);
+    }
+}