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

vitest.config.ts

@@ -0,0 +1,21 @@
+import { defineConfig } from "vitest/config"
+
+export default defineConfig({
+  test: {
+    environment: "node",
+    include: ["tests/**/*.test.ts"],
+    watch: false,
+    globals: false,
+    clearMocks: true,
+    restoreMocks: true,
+    pool: "forks",
+    fileParallelism: false,
+    testTimeout: 120_000,
+    hookTimeout: 120_000,
+  },
+  resolve: {
+    alias: {
+      "@": new URL("./src", import.meta.url).pathname,
+    },
+  },
+})