feat(network): add pointer/hand mode toggle to diagram toolbar

- Header shows MousePointer2 (select) and Hand (pan) toggle buttons
- Select mode: drag on canvas draws a selection box (selectionOnDrag)
- Pan mode: drag on canvas pans the viewport (panOnDrag)
- Space held in either mode temporarily switches to pan (panActivationKeyCode)
- Keyboard shortcuts: V = select mode, H = pan mode
- Cursor changes to grab/grabbing in pan mode

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

frontend/src/components/network/DiagramHeader.tsx

@@ -1,6 +1,9 @@
 import { useState, useCallback, useRef, useEffect } from 'react'
 import { useNavigate } from 'react-router-dom'
-import { ChevronLeft, Save, Download, FileJson, Image, FileText, Undo2, Redo2 } from 'lucide-react'
+import { ChevronLeft, Save, Download, FileJson, Image, FileText, Undo2, Redo2, MousePointer2, Hand } from 'lucide-react'
+import { cn } from '@/lib/utils'
+
+export type InteractionMode = 'select' | 'pan'
 
 interface DiagramHeaderProps {
   name: string
@@ -18,6 +21,8 @@ interface DiagramHeaderProps {
   onRedo: () => void
   canUndo: boolean
   canRedo: boolean
+  interactionMode: InteractionMode
+  onModeChange: (mode: InteractionMode) => void
 }
 
 export function DiagramHeader({
@@ -36,6 +41,8 @@ export function DiagramHeader({
   onRedo,
   canUndo,
   canRedo,
+  interactionMode,
+  onModeChange,
 }: DiagramHeaderProps) {
   const navigate = useNavigate()
   const [editing, setEditing] = useState(false)
@@ -117,6 +124,36 @@ export function DiagramHeader({
 
       <div className="mx-2 h-5 w-px bg-border-default" />
 
+      {/* Interaction mode toggle */}
+      <div className="flex items-center rounded border border-default overflow-hidden">
+        <button
+          onClick={() => onModeChange('select')}
+          title="Select (V)"
+          className={cn(
+            'p-1.5 transition-colors',
+            interactionMode === 'select'
+              ? 'bg-elevated text-primary'
+              : 'text-muted-foreground hover:text-primary hover:bg-elevated/50',
+          )}
+        >
+          <MousePointer2 size={15} />
+        </button>
+        <button
+          onClick={() => onModeChange('pan')}
+          title="Pan (H)"
+          className={cn(
+            'p-1.5 transition-colors',
+            interactionMode === 'pan'
+              ? 'bg-elevated text-primary'
+              : 'text-muted-foreground hover:text-primary hover:bg-elevated/50',
+          )}
+        >
+          <Hand size={15} />
+        </button>
+      </div>
+
+      <div className="mx-2 h-5 w-px bg-border-default" />
+
       {editing ? (
         <input
           ref={inputRef}

frontend/src/components/network/NetworkCanvas.tsx

@@ -15,6 +15,7 @@ import { nodeTypes } from './nodes/nodeTypes'
 import { edgeTypes } from './edges/edgeTypes'
 import { getDeviceRenderConfig } from './nodes/deviceRegistry'
 import type { DeviceNodeData } from './nodes/DeviceNode'
+import type { InteractionMode } from './DiagramHeader'
 
 interface NetworkCanvasProps {
   nodes: Node[]
@@ -31,6 +32,7 @@ interface NetworkCanvasProps {
   onNodeContextMenu?: (event: React.MouseEvent, node: Node) => void
   onPaneContextMenu?: (event: MouseEvent | React.MouseEvent) => void
   onPaneClick?: () => void
+  interactionMode?: InteractionMode
 }
 
 export function NetworkCanvas({
@@ -48,6 +50,7 @@ export function NetworkCanvas({
   onNodeContextMenu,
   onPaneContextMenu,
   onPaneClick: onPaneClickProp,
+  interactionMode = 'select',
 }: NetworkCanvasProps) {
   const handleSelectionChange = useCallback(({ nodes: selectedNodes, edges: selectedEdges }: { nodes: Node[]; edges: Edge[] }) => {
     if (selectedNodes.length === 1) {
@@ -93,10 +96,13 @@ export function NetworkCanvas({
         defaultEdgeOptions={{ type: 'connection' }}
         deleteKeyCode={['Backspace', 'Delete']}
         multiSelectionKeyCode="Shift"
+        panOnDrag={interactionMode === 'pan'}
+        selectionOnDrag={interactionMode === 'select'}
+        panActivationKeyCode="Space"
         snapToGrid={true}
         snapGrid={[20, 20]}
         fitView
-        className="bg-page"
+        className={interactionMode === 'pan' ? 'bg-page cursor-grab active:cursor-grabbing' : 'bg-page'}
       >
         <Background variant={BackgroundVariant.Dots} color="var(--color-border-default)" gap={20} size={1} />
         <Controls className="!border-default !bg-card [&>button]:!border-default [&>button]:!bg-card [&>button]:!fill-text-primary" />

frontend/src/components/network/hooks/useCanvasShortcuts.ts

@@ -36,6 +36,7 @@ export function useCanvasShortcuts({
   onUndo,
   onRedo,
   onNudge,
+  onSetMode,
 }: {
   nodes: Node[]
   edges: Edge[]
@@ -46,6 +47,7 @@ export function useCanvasShortcuts({
   onUndo: () => void
   onRedo: () => void
   onNudge: (dx: number, dy: number) => void
+  onSetMode: (mode: 'select' | 'pan') => void
 }) {
   const { getNodes, fitView, screenToFlowPosition, setNodes: rfSetNodes } = useReactFlow()
   const clipboardRef = useRef<ClipboardData | null>(null)
@@ -242,6 +244,16 @@ export function useCanvasShortcuts({
         return
       }
 
+      // Mode shortcuts: V = select, H = pan
+      if (!ctrl && e.key === 'v') {
+        onSetMode('select')
+        return
+      }
+      if (!ctrl && e.key === 'h') {
+        onSetMode('pan')
+        return
+      }
+
       if (ctrl && e.key === 'c') {
         e.preventDefault()
         copyNodes()
@@ -268,7 +280,7 @@ export function useCanvasShortcuts({
 
     document.addEventListener('keydown', handleKeyDown)
     return () => document.removeEventListener('keydown', handleKeyDown)
-  }, [copyNodes, pasteNodes, duplicateNodes, selectAll, fitView, bringSelectedToFront, sendSelectedToBack, onUndo, onRedo, onNudge])
+  }, [copyNodes, pasteNodes, duplicateNodes, selectAll, fitView, bringSelectedToFront, sendSelectedToBack, onUndo, onRedo, onNudge, onSetMode])
 
   return {
     copyNodes,