WebauthnAuthenticator leaks sensitive HTTP headers through INFO-level logs

Summary

## Impact

`Webauthn\Bundle\Security\Http\Authenticator\WebauthnAuthenticator` logs the full `Symfony\Component\HttpFoundation\Request` object inside the log context of both `onAuthenticationSuccess()` and `onAuthenticationFailure()` at INFO level:

```php $this->logger->info('User has been authenticated successfully with Webauthn.', [ 'request' => $request, 'firewallName' => $firewallName, 'identifier' => $token->getUserIdentifier(), ]);

$this->logger->info('Webauthn authentication request failed.', [ 'request' => $request, 'exception' => $exception, ]); ```

`Request::__toString()` returns the raw HTTP message, including every request header. As soon as the configured logger normalises or stringifies the context (default behaviour for `LineFormatter`, `JsonFormatter` via `NormalizerFormatter`, etc.), sensitive headers such as `Cookie` (session identifier), `Authorization` and any custom auth header are written to the log stream in clear text.

Applications that forward logs to centralised platforms (ELK, Splunk, Datadog and similar) are particularly exposed: log access is typically broader than application access, which can allow log readers to hijack authenticated sessions.

## Affected versions

Every release prior to 5.3.4 is affected.

## Patches

The fix removes the full `Request` object from the log context and keeps only non-sensitive fields (request path, method, firewall name, user identifier). It is shipped in 5.3.4. Older branches will not receive a backport; users on those branches should upgrade to 5.3.4+ or apply one of the workarounds below.

## Workarounds

Until the upgrade is applied, projects can:

1. Raise the minimum log level for the WebAuthn authenticator above INFO so these two log records are not emitted in production. 2. Configure their Monolog processor/formatter to strip the `request` key from the context of these records before they are written.

## Credit

Reported by Kay Joosten (Dawn Technology), maintainer of [Stepup-Webauthn](https://github.com/OpenConext/Stepup-Webauthn).