refactor(app): migrate small styles to tailwind

src/app/auth/components/__tests__/tailwind-components.test.tsx

@@ -0,0 +1,15 @@
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, expect, it } from "vitest";
+
+import { AuthErrorMessage } from "../auth-error-message";
+
+describe("auth Tailwind components", () => {
+  it("renders AuthErrorMessage only when a message is present", () => {
+    expect(renderToStaticMarkup(<AuthErrorMessage message={null} />)).toBe("");
+
+    const html = renderToStaticMarkup(<AuthErrorMessage message="Invalid email" />);
+    expect(html).toContain('role="alert"');
+    expect(html).toContain("text-error");
+    expect(html).toContain("Invalid email");
+  });
+});