startFlow static method
Starts tracking a named flow (e.g. 'registration', 'onboarding', 'login').
Call endFlow with the same name when the flow completes. If the flow was already started, it resets the start time.
Implementation
static void startFlow(String flowName, {Map<String, String>? metadata}) {
AppConfig.logger.d('[FlowTracker] Start: $flowName');
_activeFlows[flowName] = DateTime.now();
}