[BUG] flagd provider silently falls back to localhost for valid rooted FQDN hosts (trailing dot)

Observed behavior

When FlagdProvider is configured with a host that is a valid rooted/fully-qualified domain name ending in a dot (e.g. flagd.flagd.svc.cluster.local.), the provider silently ignores it and connects to localhost instead. No exception or warning is emitted, which makes this very hard to diagnose.

Expected Behavior

A rooted FQDN with a trailing dot should be accepted and used as-is. At minimum, an invalid host should raise InvalidConfigException rather than silently defaulting to localhost.

Steps to reproduce

new FlagdProvider([
    'host' => 'flagd.flagd.svc.cluster.local.', // note trailing dot
    'port' => 8013,
    'protocol' => 'http',
]);
// resolveBooleanValue(...) -> connects to http://localhost:8013, not the configured host

Start at FlagdProvider configuration handling and follow resolveBooleanValue(...) to see where the configured host is validated or replaced. Reproduce with the rooted FQDN ending in a dot; done means that host is used as-is and invalid hosts raise InvalidConfigException instead of silently falling back to localhost.