test: add initial unit integration and e2e coverage

Adds the initial testing baseline for the project:

   Unit coverage:
   - Zod schemas for items, assignments, movements, categories, auth, recipients, users, and assets
   - password hashing and verification helpers
   - auth role helper functions

   Integration coverage with PostgreSQL Testcontainers:
   - item use-cases: create, duplicate names, delete constraints
   - assignment use-cases: create, insufficient stock, return, double return
   - asset use-cases: available/assigned creation and lifecycle transitions
   - user use-cases: create/update, uniqueness, admin safeguards, password reset
   - category use-cases: create/update/delete constraints
   - recipient use-cases: create/update and uniqueness constraints

   E2E smoke coverage with Playwright:
   - unauthenticated redirect to login
   - seeded admin login
   - dashboard load
   - admin users page
   - inventory items page
   - assignments page

   Also configures:
   - Vitest
   - Playwright
   - PostgreSQL Testcontainers helpers
   - deterministic E2E admin bootstrap
   - test artifact ignores

   Validation:
   - bun run test: 9 files / 37 tests passed
   - bun run test:e2e: 3 passed
   - bunx tsc --noEmit: passed
   - bunx prisma validate: passed

tests/e2e/app.smoke.spec.ts

@@ -0,0 +1,50 @@
+import { expect, type Page, test } from "@playwright/test"
+
+async function signInAsAdmin(page: Page) {
+  await page.goto("/login")
+  await page.getByLabel("Username").fill("admin")
+  await page.getByLabel("Password").fill("admin-password")
+  await page.getByRole("button", { name: "Sign In" }).click()
+  await expect(page).toHaveURL("/")
+}
+
+test.describe("main app smoke", () => {
+  test("redirects unauthenticated users to login", async ({ page }) => {
+    await page.goto("/admin/users")
+
+    await expect(page).toHaveURL(/\/login/)
+    await expect(page.getByLabel("Username")).toBeVisible()
+    await expect(page.getByRole("button", { name: "Sign In" })).toBeVisible()
+  })
+
+  test("signs in as seeded admin and opens the dashboard", async ({ page }) => {
+    await signInAsAdmin(page)
+
+    await expect(page.getByRole("heading", { name: "Dashboard" })).toBeVisible()
+    await expect(page.getByText("E2E Admin")).toBeVisible()
+    await expect(
+      page.getByRole("link", { name: /Stock Manager/i }),
+    ).toBeVisible()
+  })
+
+  test("admin can open users and inventory pages", async ({ page }) => {
+    await signInAsAdmin(page)
+
+    await page.getByRole("link", { name: "Users" }).click()
+    await expect(page).toHaveURL(/\/admin\/users/)
+    await expect(page.getByRole("heading", { name: "Users" })).toBeVisible()
+    await expect(
+      page.getByRole("cell", { name: "admin@example.test" }),
+    ).toBeVisible()
+
+    await page.goto("/inventory/items")
+    await expect(page.getByRole("heading", { name: "Items" })).toBeVisible()
+    await expect(page.getByText("No items found.")).toBeVisible()
+
+    await page.goto("/assignments")
+    await expect(
+      page.getByRole("heading", { name: "Assignments" }),
+    ).toBeVisible()
+    await expect(page.getByText("No assignments found")).toBeVisible()
+  })
+})