MVP-0: First Field Upload — UI with Dataset Explorer, Artifact Viewer, Mission Upload

- Dataset Explorer: list missions with processing status
- Artifact Viewer: mission details, metadata, processing status
- Mission Upload: simple video upload form
- React + Vite + React Router
- Proxy to API at localhost:3000

MVP-0 Acceptance Criteria:
✅ Upload video
✅ Create mission
✅ View mission in Dataset Explorer
✅ View artifact details
✅ See processing status

No AI. Just file transfer, storage, metadata, registry.

Next: Pilot 001 — First real field upload

packages/ui/src/main.tsx

@@ -0,0 +1,12 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import { BrowserRouter } from 'react-router-dom';
+import App from './App';
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+  <React.StrictMode>
+    <BrowserRouter>
+      <App />
+    </BrowserRouter>
+  </React.StrictMode>
+);