feat: [approval] Document ↔ Approval 브릿지 연동 (Phase 4.2)

- Approval 모델에 linkable morphTo 관계 추가
- DocumentService: 상신 시 Approval 자동 생성 + approval_steps 변환
- ApprovalService: 승인/반려/회수 시 Document 상태 동기화
- approvals 테이블에 linkable_type, linkable_id 컬럼 마이그레이션

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Services/ApprovalService.php

@@ -2,6 +2,7 @@
 
 namespace App\Services;
 
+use App\Models\Documents\Document;
 use App\Models\Tenants\Approval;
 use App\Models\Tenants\ApprovalForm;
 use App\Models\Tenants\ApprovalLine;
@@ -567,7 +568,7 @@ public function show(int $id): Approval
     {
         $tenantId = $this->tenantId();
 
-        return Approval::query()
+        $approval = Approval::query()
             ->where('tenant_id', $tenantId)
             ->with([
                 'form:id,name,code,category,template',
@@ -579,6 +580,19 @@ public function show(int $id): Approval
                 'steps.approver.tenantProfile.department:id,name',
             ])
             ->findOrFail($id);
+
+        // Document 브릿지: 연결된 문서 데이터 로딩
+        if ($approval->linkable_type === Document::class) {
+            $approval->load([
+                'linkable.template',
+                'linkable.template.approvalLines',
+                'linkable.data',
+                'linkable.approvals.user:id,name',
+                'linkable.attachments',
+            ]);
+        }
+
+        return $approval;
     }
 
     /**
@@ -842,6 +856,9 @@ public function approve(int $id, ?string $comment = null): Approval
             $approval->updated_by = $userId;
             $approval->save();
 
+            // Document 브릿지 동기화
+            $this->syncToLinkedDocument($approval);
+
             return $approval->fresh([
                 'form:id,name,code,category',
                 'drafter:id,name',
@@ -895,6 +912,9 @@ public function reject(int $id, string $comment): Approval
             $approval->updated_by = $userId;
             $approval->save();
 
+            // Document 브릿지 동기화
+            $this->syncToLinkedDocument($approval);
+
             return $approval->fresh([
                 'form:id,name,code,category',
                 'drafter:id,name',
@@ -934,6 +954,9 @@ public function cancel(int $id): Approval
             $approval->updated_by = $userId;
             $approval->save();
 
+            // Document 브릿지 동기화 (steps 삭제 전에 실행)
+            $this->syncToLinkedDocument($approval);
+
             // 결재 단계들 삭제
             $approval->steps()->delete();
 
@@ -944,6 +967,57 @@ public function cancel(int $id): Approval
         });
     }
 
+    /**
+     * Approval → Document 브릿지 동기화
+     * 결재 승인/반려/회수 시 연결된 Document의 상태와 결재란을 동기화
+     */
+    private function syncToLinkedDocument(Approval $approval): void
+    {
+        if ($approval->linkable_type !== Document::class) {
+            return;
+        }
+
+        $document = Document::find($approval->linkable_id);
+        if (! $document) {
+            return;
+        }
+
+        // approval_steps → document_approvals 동기화 (승인자 이름/시각 반영)
+        foreach ($approval->steps as $step) {
+            if ($step->status === ApprovalStep::STATUS_PENDING) {
+                continue;
+            }
+
+            $docApproval = $document->approvals()
+                ->where('step', $step->step_order)
+                ->first();
+
+            if ($docApproval) {
+                $docApproval->update([
+                    'status' => strtoupper($step->status),
+                    'acted_at' => $step->acted_at,
+                    'comment' => $step->comment,
+                ]);
+            }
+        }
+
+        // Document 전체 상태 동기화
+        $documentStatus = match ($approval->status) {
+            Approval::STATUS_APPROVED => Document::STATUS_APPROVED,
+            Approval::STATUS_REJECTED => Document::STATUS_REJECTED,
+            Approval::STATUS_CANCELLED => Document::STATUS_CANCELLED,
+            default => Document::STATUS_PENDING,
+        };
+
+        $document->update([
+            'status' => $documentStatus,
+            'completed_at' => in_array($approval->status, [
+                Approval::STATUS_APPROVED,
+                Approval::STATUS_REJECTED,
+            ]) ? now() : null,
+        ]);
+    }
+
     /**
      * 참조 열람 처리
      */