fix(pwa): retire the service worker instead of just fixing it

The previous commit stopped the worker from caching build output, which
removed the cause of the blank Catalog Studio but left the worker itself
serving a purpose worth one offline fallback: three public endpoints
(/api/home, /api/online, /api/radio/config). Behind Cloudflare, for a site
whose visitors are online, that fallback rarely fires and goes stale exactly
where it is most likely to matter.

So the worker goes away rather than staying as a mostly-inert layer that every
future release still has to keep correct.

public/sw.js is not deleted, because deleting it would leave every existing
registration alive and still in control of the page, caching as it did before.
It becomes the opposite of what it was: on activate it deletes every cache,
unregisters itself and reloads open clients so they stop being controlled.
Browsers that already installed a worker therefore uninstall it on their next
visit; browsers that never had one are unaffected.

src/components/pwa-register.tsx is removed and unmounted from the root
layout, so nothing registers a worker any more and the kill switch only ever
runs for the visitors who need it.

The manifest is deliberately untouched. src/app/manifest.ts is an ordinary
Next.js route, independent of any worker, and Chrome installs from a manifest
alone, so the site stays installable on a phone.

Verified nothing depended on it: no other navigator.serviceWorker or caches.*
reference exists in the app, the theme runs from the plain /scripts/
theme-init.js script, and no Studio, catalog or import module touches a
worker. Typecheck and lint clean, 2326 unit tests and 72 UI tests green,
including every Studio and catalog spec.

src/app/layout.tsx

@@ -7,7 +7,6 @@ import { getLocale, getMessages } from "next-intl/server";
 
 import { type ReactNode, Suspense } from "react";
 import { GlobalProgressBar } from "@/components/global-progress-bar";
-import { PwaRegister } from "@/components/pwa-register";
 import { ScopedThemeVars } from "@/components/scoped-theme-vars";
 import { ThemeScopeDetector } from "@/components/theme-scope-detector";
 import { ThemeVars } from "@/components/theme-vars";
@@ -110,7 +109,6 @@ export default async function RootLayout({
 					<ScopedThemeVars nonce={nonce} />
 					<ThemeScopeDetector />
 					{children}
-					<PwaRegister />
 				</NextIntlClientProvider>
 			</body>
 		</html>

src/components/pwa-register.tsx

@@ -1,28 +0,0 @@
-"use client";
-
-import { useEffect } from "react";
-
-// Must move together with the caches in public/sw.js. It is part of the
-// registration URL, so an unchanged value means the browser never refetches
-// sw.js and keeps running the previous worker.
-const SW_VERSION = "4";
-
-export function PwaRegister() {
-	useEffect(() => {
-		if (typeof navigator === "undefined" || !("serviceWorker" in navigator))
-			return;
-
-		navigator.serviceWorker.getRegistrations().then((regs) => {
-			for (const reg of regs) {
-				reg.unregister();
-			}
-		});
-
-		navigator.serviceWorker
-			.register(`/sw.js?${SW_VERSION}`)
-			.catch((error) =>
-				console.error("[PWA] Service worker registration failed:", error),
-			);
-	}, []);
-	return null;
-}