feat(mobile): add mobile app with Expo/React Native and Laravel API endpoints

app/Models/MobileSubtask.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+
+class MobileSubtask extends Model
+{
+    use HasFactory;
+
+    protected $table = 'mobile_subtasks';
+
+    protected $fillable = [
+        'task_id',
+        'title',
+        'is_completed',
+    ];
+
+    protected $casts = [
+        'is_completed' => 'boolean',
+    ];
+
+    public function task()
+    {
+        return $this->belongsTo(MobileTask::class, 'task_id');
+    }
+}