feat(network): add undo/redo shortcuts (Ctrl+Z/Y) and arrow key nudging

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/NetworkDiagrams/DiagramEditor.tsx

@@ -113,6 +113,17 @@ function DiagramEditorInner() {
   const canUndo = historyIndex.current > 0
   const canRedo = historyIndex.current < historyStack.current.length - 1
 
+  const onNudge = useCallback((dx: number, dy: number) => {
+    const selected = nodes.filter(n => n.selected)
+    if (selected.length === 0) return
+    pushHistory(nodes, edges)
+    setNodes(prev => prev.map(n =>
+      n.selected
+        ? { ...n, position: { x: n.position.x + dx, y: n.position.y + dy } }
+        : n
+    ))
+  }, [nodes, edges, pushHistory, setNodes])
+
   const {
     copyNodes,
     pasteNodes,
@@ -127,6 +138,9 @@ function DiagramEditorInner() {
     setEdges,
     setIsDirty: (v: boolean) => setIsDirty(v),
     canvasRef,
+    onUndo: undo,
+    onRedo: redo,
+    onNudge,
   })
 
   const handleNodesChange: typeof onNodesChange = useCallback((changes) => {