NSI and tag refinement

lib/services/map_data_submodules/nodes_from_osm_api.dart

@@ -202,7 +202,11 @@ bool _nodeMatchesProfiles(Map<String, String> nodeTags, List<NodeProfile> profil
 /// Check if a node's tags match a specific profile
 bool _nodeMatchesProfile(Map<String, String> nodeTags, NodeProfile profile) {
   // All profile tags must be present in the node for it to match
+  // Skip empty values as they are for refinement purposes only
   for (final entry in profile.tags.entries) {
+    if (entry.value.trim().isEmpty) {
+      continue; // Skip empty values - they don't need to match anything
+    }
     if (nodeTags[entry.key] != entry.value) {
       return false;
     }

lib/services/map_data_submodules/nodes_from_overpass.dart

@@ -197,8 +197,9 @@ Future<List<OsmNode>> _fetchSingleOverpassQuery({
 String _buildOverpassQuery(LatLngBounds bounds, List<NodeProfile> profiles, int maxResults) {
   // Build node clauses for each profile
   final nodeClauses = profiles.map((profile) {
-    // Convert profile tags to Overpass filter format
+    // Convert profile tags to Overpass filter format, excluding empty values
     final tagFilters = profile.tags.entries
+        .where((entry) => entry.value.trim().isNotEmpty) // Skip empty values
         .map((entry) => '["${entry.key}"="${entry.value}"]')
         .join();