register method
Registers a feature flag with its default boolean state.
Stores defaultValue as the baseline fallback for clearOverrides.
If the flag signal already exists, its value is preserved; otherwise, a new signal
initialized to defaultValue is allocated.
features.register('analytics_tracking', defaultValue: true);
Implementation
void register(String flagName, {bool defaultValue = false}) {
_defaults[flagName] = defaultValue;
if (!_flags.containsKey(flagName)) {
_flags[flagName] = signal(defaultValue);
}
}