Adds first version of the app. Local storage only.

src/components/layout/AppShell.tsx

@@ -0,0 +1,34 @@
+import { useEffect } from 'react'
+import { useProjectStore } from '../../state/projectStore'
+import FlowCanvas from '../canvas/FlowCanvas'
+import DevicePalette from '../palette/DevicePalette'
+import ConnectionErrorBanner from './ConnectionErrorBanner'
+import RightPanel from './RightPanel'
+import TopBar from './TopBar'
+
+export default function AppShell() {
+  const isLoaded = useProjectStore((s) => s.isLoaded)
+  const loadFromStorage = useProjectStore((s) => s.loadFromStorage)
+
+  useEffect(() => {
+    loadFromStorage()
+  }, [loadFromStorage])
+
+  if (!isLoaded) {
+    return <div className="flex h-screen items-center justify-center text-sm text-slate-400">Loading…</div>
+  }
+
+  return (
+    <div className="flex h-screen flex-col">
+      <TopBar />
+      <div className="flex min-h-0 flex-1">
+        <DevicePalette />
+        <main className="relative min-w-0 flex-1">
+          <ConnectionErrorBanner />
+          <FlowCanvas />
+        </main>
+        <RightPanel />
+      </div>
+    </div>
+  )
+}