UI gaps: radio player widget, logo generator, public room page

Phase D of the parity push:
- Radio player: fixed bottom-right widget (port of atom's radio-player.blade)
  that streams the hotel radio via <audio>, with play/pause, volume, current
  DJ / now-playing and live listener count, polling the public API every 15s.
  A server gate (RadioPlayerGate) only mounts it when radio is enabled + a
  stream URL is set, so no widget JS ships when off. Mounted in the layout.
- Logo generator (/logo): client tool — hotel name + font/colour/size pickers
  with a live preview and "download PNG" via canvas.
- Public room page (/room/[id]): renders an emulator room (name, owner,
  users/max, state, category) in a ContentCard.

Verified live (prod, amx_test): /logo renders the generator, /room/50 shows
the real room "Dark Elegant Bundle", and with radio enabled the player
mounts fixed bottom-right (audio + play/pause + Test FM); reverted the test
settings. tsc 0, vitest 49/49, next build 0.

src/app/layout.tsx

@@ -4,6 +4,7 @@ import { getLocale, getMessages } from "next-intl/server";
 import { Nunito } from "next/font/google";
 import type { ReactNode } from "react";
 import { Navigation } from "@/components/navigation";
+import RadioPlayerGate from "@/components/public/radio-player-gate";
 import { SiteFooter } from "@/components/site-footer";
 import { SiteHeader } from "@/components/site-header";
 import { ThemeVars } from "@/components/theme-vars";
@@ -57,6 +58,7 @@ export default async function RootLayout({ children }: { children: ReactNode })
             </div>
           </main>
           <SiteFooter />
+          <RadioPlayerGate />
         </NextIntlClientProvider>
       </body>
     </html>