feat: add passkey API support for signup and login methods

[amitsingh05667]

Summary

Adds Passkey API support to auth0-react, making passkey.signup and passkey.login available through the useAuth0 hook.

Changes

• Added passkey: PasskeyApiClient to Auth0ContextInterface and exposed it via useAuth0
• Wrapped passkey.signup / passkey.login with state dispatch so isAuthenticated and user update after a successful flow
• Exported passkey error classes and types from the package root
• Added 9 tests and updated the Auth0Client mock

Usage

import { useAuth0, PasskeyError } from '@auth0/auth0-react';

function PasskeyButton() {
  const { passkey } = useAuth0();

  const handleSignup = async () => {
    try {
      await passkey.signup({ email: 'user@example.com' });
    } catch (error) {
      if (error instanceof PasskeyError) {
        console.error('Passkey error:', error.message);
      }
    }
  };

  const handleLogin = async () => {
    await passkey.login({ scope: 'openid profile email' });
  };

  return (
    <>
      <button onClick={handleSignup}>Sign up with Passkey</button>
      <button onClick={handleLogin}>Sign in with Passkey</button>
    </>
  );
}