feat: [material] 부적합관리 결재 연동 구현

- Migration: approval_id FK 추가
- Model: approval() BelongsTo 관계
- Service: submitForApproval() 결재상신 (결재문서+결재선 생성)
- ApprovalService: 승인→CLOSED, 반려/회수→approval_id 해제
- Controller: POST /{id}/submit-approval 엔드포인트
- Route: submit-approval 라우트 등록

app/Services/NonconformingReportService.php

@@ -4,6 +4,9 @@
 
 use App\Models\Materials\NonconformingReport;
 use App\Models\Materials\NonconformingReportItem;
+use App\Models\Tenants\Approval;
+use App\Models\Tenants\ApprovalLine;
+use App\Models\Tenants\ApprovalStep;
 use Illuminate\Support\Facades\DB;
 
 class NonconformingReportService extends Service
@@ -68,6 +71,9 @@ public function show(int $id): NonconformingReport
                 'actionManager:id,name',
                 'relatedEmployee:id,name',
                 'files',
+                'approval:id,document_number,status,completed_at',
+                'approval.steps:id,approval_id,step_order,step_type,approver_id,status,comment,acted_at',
+                'approval.steps.approver:id,name',
             ])
             ->findOrFail($id);
     }
@@ -235,6 +241,80 @@ public function stats(array $params): array
         ];
     }
 
+    /**
+     * 결재상신 (RESOLVED 상태에서만 가능)
+     */
+    public function submitForApproval(int $id, array $data): NonconformingReport
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        return DB::transaction(function () use ($id, $data, $tenantId, $userId) {
+            $report = NonconformingReport::query()
+                ->where('tenant_id', $tenantId)
+                ->findOrFail($id);
+
+            if ($report->status !== NonconformingReport::STATUS_RESOLVED) {
+                abort(422, __('error.nonconforming.must_be_resolved_for_approval'));
+            }
+
+            if ($report->approval_id) {
+                abort(422, __('error.nonconforming.approval_already_exists'));
+            }
+
+            $steps = $data['steps'] ?? [];
+            if (empty($steps)) {
+                abort(422, __('error.approval.steps_required'));
+            }
+
+            // 결재 문서 생성
+            $approval = Approval::create([
+                'tenant_id' => $tenantId,
+                'document_number' => $this->generateApprovalNumber($tenantId),
+                'form_id' => $data['form_id'] ?? null,
+                'title' => $data['title'] ?? "부적합 처리 결재 - {$report->nc_number}",
+                'content' => [
+                    'nc_number' => $report->nc_number,
+                    'nc_type' => $report->nc_type,
+                    'site_name' => $report->site_name,
+                    'defect_description' => $report->defect_description,
+                    'cause_analysis' => $report->cause_analysis,
+                    'corrective_action' => $report->corrective_action,
+                    'total_cost' => $report->total_cost,
+                ],
+                'status' => Approval::STATUS_PENDING,
+                'drafter_id' => $userId,
+                'department_id' => $report->department_id,
+                'drafted_at' => now(),
+                'current_step' => 1,
+                'linkable_type' => NonconformingReport::class,
+                'linkable_id' => $report->id,
+                'created_by' => $userId,
+                'updated_by' => $userId,
+            ]);
+
+            // 결재선 단계 생성
+            foreach ($steps as $index => $step) {
+                ApprovalStep::create([
+                    'tenant_id' => $tenantId,
+                    'approval_id' => $approval->id,
+                    'step_order' => $index + 1,
+                    'step_type' => $step['step_type'] ?? ApprovalLine::STEP_TYPE_APPROVAL,
+                    'approver_id' => $step['approver_id'],
+                    'status' => ApprovalStep::STATUS_PENDING,
+                ]);
+            }
+
+            // 보고서에 결재 연결
+            $report->update([
+                'approval_id' => $approval->id,
+                'updated_by' => $userId,
+            ]);
+
+            return $this->show($report->id);
+        });
+    }
+
     // ── private ──
 
     /**
@@ -298,6 +378,26 @@ private function sumItemAmounts(array $items): int
         return $total;
     }
 
+    /**
+     * 결재 문서번호 생성
+     */
+    private function generateApprovalNumber(int $tenantId): string
+    {
+        $prefix = 'AP';
+        $date = now()->format('Ymd');
+        $pattern = "{$prefix}-{$date}-";
+
+        $lastNumber = Approval::withTrashed()
+            ->where('tenant_id', $tenantId)
+            ->where('document_number', 'like', "{$pattern}%")
+            ->orderByDesc('document_number')
+            ->value('document_number');
+
+        $seq = $lastNumber ? ((int) substr($lastNumber, -4) + 1) : 1;
+
+        return sprintf('%s-%s-%04d', $prefix, $date, $seq);
+    }
+
     /**
      * 상태 전이 검증
      */