reject cross-origin websocket handshakes

Neither /ws nor the jsmpeg websockets checked Origin, and the internal port grants admin to everyone, so any page a LAN user visited could open ws://frigate:5000/ws and send commands or read streams. Both servers now reject a browser handshake whose Origin host matches neither Host nor X-Forwarded-Host, and allow handshakes without an Origin for non-browser clients. nginx now forwards an outer proxy's X-Forwarded-Host instead of overwriting it, so proxies that rewrite Host and the Home Assistant integration's proxy still match.

web/vite.config.ts

@@ -28,7 +28,6 @@ export default defineConfig({
       },
       "/live": {
         target: `ws://${proxyHost}`,
-        changeOrigin: true,
         ws: true,
       },
     },