fix(admin,server): 上传改用 file.buffer 并移除手写 multipart 头

apps/admin/src/pages/Occupancies/useOccupancyMutations.ts

@@ -44,9 +44,7 @@ export function useOccupancyMutations() {
   );
   const importMutation = useApiMutation(
     async ({ formData, params }: { formData: FormData; params: string }) =>
-      api.post(`/occupancies/import?${params}`, formData, {
-        headers: { 'Content-Type': 'multipart/form-data' },
-      }),
+      api.post(`/occupancies/import?${params}`, formData),
     { invalidate: invalidateOccupancies },
   );