完成五人团队正式内用最小收口（07-18-small-team-internal-readiness）

client/src/api/reimbursements.ts

@@ -505,11 +505,12 @@ export async function uploadReimbursementAttachments(reimbursementId: string, fi
   );
 }
 
-export async function deleteReimbursementAttachment(reimbursementId: string, attachmentId: string) {
+export async function deleteReimbursementAttachment(reimbursementId: string, attachmentId: string, reason: string) {
   return apiRequestData<{ attachmentId: string; outcome: string }>(
     `/api/reimbursements/${reimbursementId}/attachments/${attachmentId}`,
     {
       method: "DELETE",
+      body: JSON.stringify({ reason }),
     },
   );
 }