update saleinvoice single and create return from sale form, update agent.md file,

src/app/shared/components/key-value.component/key-value.component.ts

@@ -1,3 +1,4 @@
+import { Maybe } from '@/core';
 import { formatDurationToText, formatJalali, JALALI_DATE_FORMATS } from '@/utils';
 import priceMaskUtils from '@/utils/price-mask.utils';
 import { CommonModule } from '@angular/common';
@@ -16,7 +17,7 @@ import { TDataType } from '../pageDataList/page-data-list.component';
 })
 export class KeyValueComponent {
   @Input() label!: string;
-  @Input() value?: string | boolean | number;
+  @Input() value?: Maybe<string | boolean | number>;
   @Input() hint?: string;
   @Input() alignment?: 'start' | 'center' | 'end' = 'start';
   @Input() type: TDataType = 'simple';