customSettings
Custom settings defined by the client application.
Clients can extend the built-in settings with app-specific preferences (e.g., "Avoid unpaved roads", "Prefer scenic routes", "Eco mode"). Keys are client-defined strings, values are boolean toggle states.
The AA settings screen can display these as additional toggle rows via SettingsProvider.getCustomSettingKeys.
Contract
Implementors of SettingsProvider must ensure that the values in this map are consistent with the values returned by SettingsProvider.getCustomSettingKeys. Both sources must reflect the same underlying preference state. When SettingsProvider.updateCustomSetting is called, the implementor should update both the underlying preferences AND emit a new AASettingsState with the updated customSettings map via the SettingsProvider.settingsState StateFlow.