feat(e2e): add Playwright end-to-end tests for authentication, GRN, production, stock transfers, and adjustments

- Introduced Playwright configuration for e2e testing.
- Implemented authentication tests to validate login functionality.
- Created tests for GRN (Goods Receipt Note) to ensure proper stock handling.
- Developed production run tests to verify lifecycle and stock posting.
- Added stock transfer tests to check movement between warehouses.
- Implemented stock adjustment tests for positive and negative adjustments.
- Established API seeder for test data setup and verification.
- Enhanced utility functions for UI interactions and response handling.

Testing/e2e/specs/stock-adjustments.spec.ts

@@ -0,0 +1,65 @@
+import { test, expect, APIRequestContext } from "@playwright/test"
+import { ApiSeeder, newApiContext, Warehouse, Item, Uom, Vendor } from "../support/api"
+import { StockAdjustmentNewPage } from "../pages/StockPages"
+
+// Stock adjustment flow (Backend/ERPCore/Controllers/StockAdjustmentsController.cs,
+// Frontend app/dashboard/stock/adjustments/new): posts immediately, no draft state
+// (Backend/ERPCore/Dtos/Stock/AdjustmentDtos.cs - QtyDelta is a signed base-UOM delta).
+test.describe("Stock adjustments", () => {
+  let api: APIRequestContext
+  let seeder: ApiSeeder
+  let warehouse: Warehouse
+  let vendor: Vendor
+  let uom: Uom
+  let item: Item
+
+  test.beforeAll(async () => {
+    api = await newApiContext()
+    seeder = new ApiSeeder(api)
+    warehouse = await seeder.firstWarehouse()
+    uom = await seeder.firstUom()
+    vendor = await seeder.createVendor()
+    item = await seeder.createItem({ namePrefix: "Adjustment Test Item" })
+
+    await seeder.receiveStock({
+      warehouseId: warehouse.warehouseId,
+      vendorId: vendor.vendorId,
+      itemId: item.itemId,
+      uomId: uom.uomId,
+      qty: 20,
+      unitCost: 30,
+    })
+  })
+
+  test.afterAll(async () => {
+    await api.dispose()
+  })
+
+  test("positive adjustment increases on-hand and shows the posted doc number", async ({ page }) => {
+    const before = await seeder.stockOnHand(item.itemId, warehouse.warehouseId)
+
+    const newPage = new StockAdjustmentNewPage(page)
+    await newPage.goto()
+    await newPage.fill({ warehouse: warehouse.name, reasonCode: "System Correction", item: item.name, qtyDelta: 5 })
+    await newPage.submit()
+
+    await newPage.expectPosted()
+
+    const after = await seeder.stockOnHand(item.itemId, warehouse.warehouseId)
+    expect(after.onHand).toBeCloseTo(before.onHand + 5, 4)
+  })
+
+  test("negative adjustment decreases on-hand", async ({ page }) => {
+    const before = await seeder.stockOnHand(item.itemId, warehouse.warehouseId)
+
+    const newPage = new StockAdjustmentNewPage(page)
+    await newPage.goto()
+    await newPage.fill({ warehouse: warehouse.name, reasonCode: "Damage", item: item.name, qtyDelta: -3 })
+    await newPage.submit()
+
+    await newPage.expectPosted()
+
+    const after = await seeder.stockOnHand(item.itemId, warehouse.warehouseId)
+    expect(after.onHand).toBeCloseTo(before.onHand - 3, 4)
+  })
+})