Change branching rule node color to dark teal for better text contrast

Co-authored-by: dwarwick <15970276+dwarwick@users.noreply.github.com>

Author: Copilot

JwtIdentity.Client/Pages/Survey/BranchingSurveyEdit.razor.cs

@@ -449,7 +449,9 @@ private void BuildSyncfusionDiagram()
             Nodes = new DiagramObjectCollection<Node>();
             Connectors = new DiagramObjectCollection<Connector>();
 
-            string choiceNodeColor = "#f5d671";
+            // Use dark teal for branching rule nodes - provides excellent contrast with white text
+            // and is visually distinct from all group colors
+            string choiceNodeColor = "#00796B";
 
             if (Survey == null || QuestionGroups == null || !QuestionGroups.Any())
                 return;