This PR introduces two new utility methods

• isFirstPage(): Returns true if the current position is at the start of the history stack.
• isLastPage(): Returns true if the current position is at the end of the history stack.

These methods are particularly useful in a testing context. For example, they enable clearer and more targeted assertions, such as:

$this->assertTrue($client->getHistory()->isLastPage());
$this->assertTrue($client->getHistory()->isFirstPage());
$this->assertFalse($client->getHistory()->isFirstPage());
$this->assertFalse($client->getHistory()->isLastPage());

These new methods also allow developers to proactively check the navigation state before calling back() or forward(), which can be useful in certain scenarios to avoid unnecessary exceptions and reduce the need for additional error handling logic.