feat: add saving storage states

[veljkho]

Adds support for Playwright's storage state feature, allowing tests to save and restore browser context state (cookies and localStorage). The primary use case is skipping repetitive login flows across tests.

After a login flow, save the authenticated state:

// tests/Browser/Auth/LoginTest.php
test('store authenticated state', function (): void {
    visit('/login')
        ->fill('#email', 'admin@example.com')
        ->fill('#password', 'secret')
        ->click('Login')
        ->assertUrlContains('/dashboard')
        ->saveStorageState('admin');
});

All other tests just reuse it:

// tests/Browser/DashboardTest.php
test('can see dashboard', function (): void {
    visit('/dashboard')
        ->withStorageState('admin')
        ->assertSee('Welcome back');
});

test('can see settings', function (): void {
    visit('/settings')
        ->withStorageState('admin')
        ->assertSee('Account Settings');
});

This is a nice feature in Playwright, would be great to see it also in Pest.