fix : 모델, BOM 구성 수정

- 설계용 모델, BOM 기능 추가

app/Models/Design/BomTemplate.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace App\Models\Design;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+class BomTemplate extends Model
+{
+    use SoftDeletes;
+
+    protected $table = 'bom_templates';
+
+    protected $fillable = [
+        'tenant_id','model_version_id','name','is_primary','notes',
+    ];
+
+    protected $casts = [
+        'is_primary' => 'boolean',
+    ];
+
+    public function modelVersion() {
+        return $this->belongsTo(ModelVersion::class, 'model_version_id');
+    }
+
+    public function items() {
+        return $this->hasMany(BomTemplateItem::class, 'bom_template_id');
+    }
+}