feat(liveview): header View link opens active design as read-only canvas

Add an authenticated GET /api/v1/liveview/config endpoint exposing the
configured LIVEVIEW_KEY to logged-in admins, so the UI builds a
ready-to-use share link. The header View button opens
/view?key=...&design=<activeDesignId>; LiveView forwards ?design=<id>
to the public endpoint, which renders that design's canvas.

ha-relevant: maybe

frontend/src/components/LiveView.tsx

@@ -68,10 +68,14 @@ function LiveViewCanvas() {
     }
 
     // Already handled synchronously in useState initializer
-    const key = new URLSearchParams(window.location.search).get('key')
+    const search = new URLSearchParams(window.location.search)
+    const key = search.get('key')
     if (!key) return
+    // Optional ?design=<id> selects which canvas to render; backend falls back
+    // to the first design when omitted.
+    const design = search.get('design') ?? undefined
 
-    liveviewApi.load(key)
+    liveviewApi.load(key, design)
       .then((res) => {
         const { nodes: apiNodes, edges: apiEdges } = res.data
         const proxmoxMap = new Map<string, boolean>(

frontend/src/components/__tests__/LiveView.test.tsx

@@ -118,7 +118,15 @@ describe('LiveView (non-standalone)', () => {
     await waitFor(() => {
       expect(screen.getByTestId('react-flow')).toBeDefined()
     })
-    expect(liveviewApi.load).toHaveBeenCalledWith('correct-key')
+    expect(liveviewApi.load).toHaveBeenCalledWith('correct-key', undefined)
+  })
+
+  it('forwards ?design=<id> to the API so a specific canvas is loaded', async () => {
+    setSearch('?key=correct-key&design=elec-123')
+    vi.mocked(liveviewApi.load).mockResolvedValue(canvasPayload as never)
+    render(<LiveView />)
+    await waitFor(() => expect(screen.getByTestId('react-flow')).toBeDefined())
+    expect(liveviewApi.load).toHaveBeenCalledWith('correct-key', 'elec-123')
   })
 
   it('allows zooming out to 0.25 so large infra fits (matches the editor)', async () => {

frontend/src/components/panels/Toolbar.tsx

@@ -1,5 +1,5 @@
 import { useRef } from 'react'
-import { Save, LayoutDashboard, Download, Palette, Undo2, Redo2, HelpCircle, Table2, FileDown, Upload } from 'lucide-react'
+import { Save, LayoutDashboard, Download, Palette, Undo2, Redo2, HelpCircle, Table2, FileDown, Upload, Eye } from 'lucide-react'
 import { Button } from '@/components/ui/button'
 import { Logo } from '@/components/ui/Logo'
 import { useCanvasStore } from '@/stores/canvasStore'
@@ -15,9 +15,10 @@ interface ToolbarProps {
   onExportMd: () => void
   onExportYaml: () => void
   onImportYaml: (content: string) => void
+  onViewOnly: () => void
 }
 
-export function Toolbar({ onSave, onAutoLayout, onExport, onChangeStyle, onUndo, onRedo, onShortcuts, onExportMd, onExportYaml, onImportYaml }: ToolbarProps) {
+export function Toolbar({ onSave, onAutoLayout, onExport, onChangeStyle, onUndo, onRedo, onShortcuts, onExportMd, onExportYaml, onImportYaml, onViewOnly }: ToolbarProps) {
   const { hasUnsavedChanges, past, future } = useCanvasStore()
   const fileInputRef = useRef<HTMLInputElement>(null)
 
@@ -81,6 +82,9 @@ export function Toolbar({ onSave, onAutoLayout, onExport, onChangeStyle, onUndo,
       <Button size="sm" variant="ghost" className="gap-1.5 text-muted-foreground hover:text-foreground cursor-pointer hover:bg-[#21262d]" onClick={onExportMd} title="Copy inventory as Markdown table">
         <Table2 size={14} /> MD
       </Button>
+      <Button size="sm" variant="ghost" className="gap-1.5 text-muted-foreground hover:text-foreground cursor-pointer hover:bg-[#21262d]" onClick={onViewOnly} title="Open read-only live view of this canvas">
+        <Eye size={14} /> View
+      </Button>
       <Button size="sm" variant="ghost" className="gap-1.5 text-muted-foreground hover:text-foreground cursor-pointer hover:bg-[#21262d]" onClick={onShortcuts} title="Keyboard shortcuts (?)">
         <HelpCircle size={14} />
       </Button>