feat: apply ingress path to app paths

When serving Frigate at a subpath, the paths that show in the URL bar
and that wind up in your browser history are anchored at the web root.
I.e. you go to `https://example.com/frigate/`, it changes to
`https://example.com/`, and clicking around works as expected, but the
`frigate/` prefix is gone.

It's confusing if you don't know that the URL's are entirely virtual.
Also, your browser history is useless, since the URL's point to e.g.
`https://example.com/#kitchen`, but visiting that URL will not hit
`/frigate/` at all.

Most of the work is already done. Nginx injects javascript to set
`window.baseURL` based on the X-Ingress-Path header. This change passes
that to BrowserRouter, so that it'll be part of the URL's it shows.

Fixes #4526

web/src/App.tsx

@@ -24,7 +24,7 @@ const Logs = lazy(() => import("@/pages/Logs"));
 function App() {
   return (
     <Providers>
-      <BrowserRouter>
+      <BrowserRouter basename={window.baseUrl}>
         <Wrapper>
           <div className="size-full overflow-hidden">
             {isDesktop && <Sidebar />}