feat(attachments): create Attachment model and migration for file attachments

app/Domains/Attachable/Models/Attachment.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace App\Domains\Attachable\Models;
+
+use Illuminate\Database\Eloquent\Attributes\Fillable;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\MorphTo;
+
+#[Fillable([
+    'attachable_type',
+    'attachable_id',
+    'path',
+    'filename',
+    'type',
+    'mime_type',
+    'is_public',
+    'extension',
+    'size',
+])]
+class Attachment extends Model
+{
+    use HasFactory;
+
+    protected $table = 'attachments';
+
+    protected function casts(): array
+    {
+        return [
+            'attachable_id' => 'integer',
+            'is_public' => 'boolean',
+            'size' => 'integer',
+        ];
+    }
+
+    /**
+     * @return MorphTo<Model, $this>
+     */
+    public function attachable(): MorphTo
+    {
+        return $this->morphTo();
+    }
+}