feat(dashboard): React+Vite SPA for the claw-store HTTP API

Single-page app with NodeCard, HotTierChart, SyncQueueCard,
SnapshotTimeline, and ProjectBrowser. Hits the new HTTP/SSE
API surface in claw-store serve (next commit). Built with
Vite/Tailwind/lucide-react; consumed by mounting the dist/
output at /usr/share/claw-store/static (or wherever
--static-dir points) and serving via claw-store serve.

dashboard/src/main.tsx

@@ -0,0 +1,10 @@
+import { StrictMode } from 'react'
+import { createRoot } from 'react-dom/client'
+import './index.css'
+import App from './App.tsx'
+
+createRoot(document.getElementById('root')!).render(
+  <StrictMode>
+    <App />
+  </StrictMode>,
+)