fix(useEdgeConnection): ensure single outgoing connection per source handle

Filter existing edges before adding new connection to prevent multiple outgoing edges from the same source handle, with special handling for switch nodes

Author: Kshitiz1403

src/lib/src/hooks/useEdgeConnection.js

@@ -97,7 +97,19 @@ export const useEdgeConnection = (edges, updateEdges, setHistoryState, nodes, wo
       newEdge.label = `→ ${targetNode?.data?.name || targetNode?.data?.label || 'next'}`;
     }
 
-    const updatedEdges = addEdge(newEdge, edges);
+    // Remove existing outgoing edges from the same source handle to ensure only one connection per handle
+    let filteredEdges = edges;
+    if (sourceNode?.type === 'switch') {
+      // For switch nodes, only remove edges from the same source handle
+      filteredEdges = edges.filter(edge => 
+        !(edge.source === connection.source && edge.sourceHandle === connection.sourceHandle)
+      );
+    } else {
+      // For non-switch nodes, remove all existing outgoing edges
+      filteredEdges = edges.filter(edge => edge.source !== connection.source);
+    }
+    
+    const updatedEdges = addEdge(newEdge, filteredEdges);
     updateEdges(updatedEdges);
 
     // Update history if setHistoryState is provided