feat: ERD 자동 생성 시스템 구축 및 모델 오류 수정

- GraphViz 설치를 통한 ERD 다이어그램 생성 지원
- BelongsToTenantTrait → BelongsToTenant 트레잇명 수정
- Estimate, EstimateItem 모델의 인터페이스 참조 오류 해결
- 60개 모델의 완전한 관계도 생성 (graph.png, 4.1MB)
- beyondcode/laravel-er-diagram-generator 패키지 활용

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/Models/Estimate/Estimate.php

@@ -3,17 +3,16 @@
 namespace App\Models\Estimate;
 
 use App\Models\Commons\Category;
-use App\Models\Contracts\BelongsToTenant;
-use App\Traits\BelongsToTenantTrait;
+use App\Traits\BelongsToTenant;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\HasMany;
 use Illuminate\Database\Eloquent\SoftDeletes;
 
-class Estimate extends Model implements BelongsToTenant
+class Estimate extends Model
 {
-    use HasFactory, SoftDeletes, BelongsToTenantTrait;
+    use HasFactory, SoftDeletes, BelongsToTenant;
 
     protected $fillable = [
         'tenant_id',

app/Models/Estimate/EstimateItem.php

@@ -2,16 +2,15 @@
 
 namespace App\Models\Estimate;
 
-use App\Models\Contracts\BelongsToTenant;
-use App\Traits\BelongsToTenantTrait;
+use App\Traits\BelongsToTenant;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\SoftDeletes;
 
-class EstimateItem extends Model implements BelongsToTenant
+class EstimateItem extends Model
 {
-    use HasFactory, SoftDeletes, BelongsToTenantTrait;
+    use HasFactory, SoftDeletes, BelongsToTenant;
 
     protected $fillable = [
         'tenant_id',