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

backend/app/Models/Quest.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+
+class Quest extends Model
+{
+    use HasFactory;
+
+    protected $fillable = [
+        'user_id',
+        'task_id',
+        'title',
+        'category',
+        'due_date',
+        'xp_reward',
+        'is_completed'
+    ];
+
+    public function user()
+    {
+        return $this->belongsTo(User::class);
+    }
+
+    public function task()
+    {
+        return $this->belongsTo(Task::class);
+    }
+}