1.47.0

(feat): Add opt-in support for a structured User-Agent header on generated SDK clients for better runtime/platform observability. When enabled, the header takes the form {sdkName}/{sdkVersion} ({os}; {arch}) Go/{version}, where the operating system (runtime.GOOS), architecture (runtime.GOARCH), and Go runtime version (runtime.Version()) are all resolved at runtime; unknown components are omitted rather than reported as empty. This behavior is gated behind a new includePlatformHeaders config option and is disabled by default, so existing generated output is unchanged. When enabled it is still subject to omitFernHeaders and is omitted when that is set.