feat(auth): implement user authentication system

backend/node_modules/zod/src/v4/classic/tests/anyunknown.test.ts

@@ -0,0 +1,26 @@
+import { expect, expectTypeOf, test } from "vitest";
+
+import * as z from "zod/v4";
+
+test("check any inference", () => {
+  const t1 = z.any();
+  t1.optional();
+  t1.nullable();
+  type t1 = z.infer<typeof t1>;
+  expectTypeOf<t1>().toEqualTypeOf<any>();
+});
+
+test("check unknown inference", () => {
+  const t1 = z.unknown();
+  t1.optional();
+  t1.nullable();
+  type t1 = z.infer<typeof t1>;
+  expectTypeOf<t1>().toEqualTypeOf<unknown>();
+});
+
+test("check never inference", () => {
+  const t1 = z.never();
+  expect(() => t1.parse(undefined)).toThrow();
+  expect(() => t1.parse("asdf")).toThrow();
+  expect(() => t1.parse(null)).toThrow();
+});