feat(API): Model 및 관계 추가

- HandoverReport, HandoverReportItem, HandoverReportManager 모델 추가
- SiteBriefing 모델 추가
- StructureReview, FcmSendLog, Position, Salary 수정
- Order 모델 정리

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

app/Models/FcmSendLog.php

@@ -131,4 +131,4 @@ public function markAsFailed(string $errorMessage): void
             'completed_at' => now(),
         ]);
     }
-}
+}