feat(web): formulario de documentos de ventas y compras (cargar, crear, actualizar con If-Match, navegar)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

apps/web/src/app/features/documents/line-columns.spec.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { DOCUMENT_LINE_COLUMNS, ITEMS_MULTI_ADD, newDocumentLine, recalcLine } from './line-columns';
+import { DOCUMENT_LINE_COLUMNS, ITEMS_MULTI_ADD, lineColumnsFor, newDocumentLine, recalcLine } from './line-columns';
 
 describe('recalcLine', () => {
   it('total = cantidad × precio, redondeado a 2 decimales', () => {
@@ -59,3 +59,12 @@ describe('línea nueva y "catálogo completo"', () => {
     expect(ITEMS_MULTI_ADD.toLine({ ItemCode: 'I9', ItemName: 'Cable' })).toMatchObject({ ItemCode: 'I9', ItemDescription: 'Cable', Quantity: 1 });
   });
 });
+
+describe('lineColumnsFor', () => {
+  it('ventas conserva las columnas; compras cambia el maestro de impuestos', () => {
+    expect(lineColumnsFor('SalesTaxCodes')).toBe(DOCUMENT_LINE_COLUMNS);
+    const tax = lineColumnsFor('PurchaseTaxCodes').find((c) => c.key === 'TaxCode');
+    expect(tax?.lookup?.config.resource).toBe('PurchaseTaxCodes');
+    expect(DOCUMENT_LINE_COLUMNS.find((c) => c.key === 'TaxCode')?.lookup?.config.resource).toBe('SalesTaxCodes');
+  });
+});