feat(reports): inventory valuation report.

feat(reports): sales by items report.
feat(reports): purchases by items report.

server/src/interfaces/IInventoryValuationSheet.ts

@@ -0,0 +1,42 @@
+import {
+  INumberFormatQuery,
+  IFormatNumberSettings,
+} from './FinancialStatements';
+
+export interface IInventoryValuationReportQuery {
+  asDate: Date | string;
+  numberFormat: INumberFormatQuery;
+  noneTransactions: boolean;  
+};
+
+export interface IInventoryValuationSheetMeta {
+  organizationName: string,
+  baseCurrency: string,
+};
+
+export interface IInventoryValuationItem {
+  id: number,
+  name: string,
+  code: string,
+  valuation: number,
+  quantity: number,
+  average: number,
+  valuationFormatted: string,
+  quantityFormatted: string,
+  averageFormatted: string,
+  currencyCode: string,
+};
+
+export interface IInventoryValuationTotal {
+  valuation: number,
+  quantity: number,
+  
+  valuationFormatted: string,
+  quantityFormatted: string,
+}
+
+export interface IInventoryValuationStatement {
+  items: IInventoryValuationItem[],
+  total: IInventoryValuationTotal
+};
+