fix : 모델, BOM 구성 수정

- 설계용 모델, BOM 기능 추가

app/Models/Design/ModelVersion.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Models\Design;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+class ModelVersion extends Model
+{
+    use SoftDeletes;
+
+    protected $table = 'model_versions';
+
+    protected $fillable = [
+        'tenant_id','model_id','version_no','status','effective_from','effective_to','notes','is_active',
+    ];
+
+    protected $casts = [
+        'is_active' => 'boolean',
+        'effective_from' => 'datetime',
+        'effective_to' => 'datetime',
+    ];
+
+    public function model() {
+        return $this->belongsTo(DesignModel::class, 'model_id');
+    }
+
+    public function bomTemplates() {
+        return $this->hasMany(BomTemplate::class, 'model_version_id');
+    }
+
+    public function scopeReleased($q) {
+        return $q->where('status', 'RELEASED');
+    }
+}