fix(network): surface connect tool and middle-pan

frontend/src/components/network/NetworkCanvas.tsx

@@ -17,6 +17,7 @@ import { edgeTypes } from './edges/edgeTypes'
 import { getDeviceRenderConfig } from './nodes/deviceRegistry'
 import type { DeviceNodeData } from './nodes/DeviceNode'
 import type { InteractionMode } from './DiagramHeader'
+import { cn } from '@/lib/utils'
 
 interface NetworkCanvasProps {
   nodes: Node[]
@@ -81,7 +82,15 @@ export function NetworkCanvas({
   }, [])
 
   return (
-    <div className="relative h-full w-full" onDragLeave={onDragLeave}>
+    <div
+      className="relative h-full w-full"
+      onDragLeave={onDragLeave}
+      onMouseDownCapture={(event) => {
+        if (event.button === 1) {
+          event.preventDefault()
+        }
+      }}
+    >
       <ReactFlow
         nodes={nodes}
         edges={edges}