Add error handling and update documentation

lib/dev_config.dart

@@ -77,6 +77,7 @@ const bool kEnableNodeExtraction = false; // Set to true to enable extract from
 
 /// Navigation availability: only dev builds, and only when online
 bool enableNavigationFeatures({required bool offlineMode}) {
+  return true;
   if (!kEnableDevelopmentModes) {
     return false; // Release builds: never allow navigation
   } else {

lib/services/routing_service.dart

@@ -84,9 +84,8 @@ class RoutingService {
       // Check alprwatch response status
       final ok = data['ok'] as bool? ?? false;
       if ( ! ok ) {
-        final code = data['error']['code'] as String? ?? 'Unknown routing error code';
-        final message = data['error']['message'] as String? ?? 'Unknown routing error';
-        throw RoutingException('alprwatch error ($code): $message');
+        final message = data['error'] as String? ?? 'Unknown routing error';
+        throw RoutingException('alprwatch error: $message');
       }
       
       final route = data['result']['route'] as Map<String, dynamic>?;