refactor: move backend in apps/backend

apps/backend/app/Models/Task.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace apps\backend\app\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class Task extends Model
+{
+    protected $fillable = [
+        'name',
+        'start',
+        'end',
+        'location',
+        'description',
+        'max_participants',
+    ];
+
+    public function event() {
+        return $this->belongsTo(Event::class);
+    }
+
+    public function users() {
+        return $this->belongsToMany(User::class);
+    }
+
+}