UPDATE: Adds web app (#79)

Things missing:

* Browse mode
* Front end tests
* Storybook

webapp/src/main.tsx

@@ -0,0 +1,15 @@
+import React from "react";
+import ReactDOM from "react-dom/client";
+import App from "./App.tsx";
+import "./index.css";
+import ThemeProvider from "@mui/material/styles/ThemeProvider";
+import { theme } from "./theme.ts";
+
+// biome-ignore lint: we know the 'root' element exists.
+ReactDOM.createRoot(document.getElementById("root")!).render(
+  <React.StrictMode>
+    <ThemeProvider theme={theme}>
+      <App />
+    </ThemeProvider>
+  </React.StrictMode>,
+);