Web frontend: perf panel, cover warmup, incremental browse rendering

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/main.tsx

@@ -2,6 +2,7 @@ import { StrictMode } from "react";
 import { createRoot } from "react-dom/client";
 
 import { App } from "./App";
+import { PERF } from "./lib/perfSettings";
 import "./styles/app.css";
 import "./styles/room.css";
 import "./styles/tippen.css";
@@ -15,8 +16,20 @@ createRoot(document.getElementById("root")!).render(
 // Registered after load so it never competes with the first paint. It is what makes
 // iOS offer "Zum Home-Bildschirm" as an app rather than a bookmark; see public/sw.js
 // for what it does and deliberately does not cache.
+//
+// Not under `?pi=1`: that is the kiosk, which *is* the server. There is nothing to
+// install, and the worker only adds a fetch handler (and a `cache.put` of every response)
+// in front of requests that are already on localhost. Any worker an earlier visit left
+// behind is removed so the kiosk stops paying for it.
 if ("serviceWorker" in navigator && import.meta.env.PROD) {
   window.addEventListener("load", () => {
+    if (!PERF.serviceWorker) {
+      void navigator.serviceWorker
+        .getRegistrations()
+        .then((registrations) => Promise.all(registrations.map((r) => r.unregister())))
+        .catch(() => undefined);
+      return;
+    }
     void navigator.serviceWorker.register("/sw.js").catch(() => {
       // A plain http:// origin that is not localhost cannot register one. The app
       // works exactly the same, it just cannot be installed.