Fix Cytoscape.js crash on navigation away from network map

- Stop running layout before destroy to prevent async callbacks hitting null renderer
- Set wheelSensitivity to 1 (default) to suppress console warning

assets/js/app.ts

@@ -588,6 +588,11 @@ const NetworkMap = {
 
   destroyed(this: any) {
     if (this.cy) {
+      // Stop any running layout before destroying to prevent async callbacks
+      // from accessing a destroyed renderer
+      try {
+        this.cy.stop()
+      } catch (_e) { /* ignore */ }
       this.cy.destroy()
       this.cy = null
     }
@@ -803,7 +808,7 @@ const NetworkMap = {
       },
       minZoom: 0.2,
       maxZoom: 3,
-      wheelSensitivity: 0.2
+      wheelSensitivity: 1
     })
 
     // Add click handler for nodes