Lobby: leagues are play buttons w/ arrow; remove background music feature

- OnlineLobbyScreen: each league row is now a tappable play button (queues a
  ranked match at that league's stake) with a forward arrow; the cheapest
  enterable league is highlighted gold. Drops the redundant separate "ranked
  random" CTA and the select-then-play step.
- Remove the background-music feature entirely: deleted the floating MusicToggle,
  the TopBar music button, and the Profile audio music toggle + style picker.
  sound.startMusic() is now an inert no-op so music never plays (sfx unchanged).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/online/TopBar.tsx

@@ -1,8 +1,7 @@
 "use client";
 
-import { Bell, Crown, Gift, Music, Store } from "lucide-react";
+import { Bell, Crown, Gift, Store } from "lucide-react";
 import { useSessionStore } from "@/lib/session-store";
-import { useSoundStore } from "@/lib/sound-store";
 import { useUIStore } from "@/lib/ui-store";
 import { useNotifStore } from "@/lib/notification-store";
 import { useI18n } from "@/lib/i18n";
@@ -15,8 +14,6 @@ export function TopBar() {
   const go = useUIStore((s) => s.go);
   const openDaily = useUIStore((s) => s.openDaily);
   const unread = useNotifStore((s) => s.unread);
-  const music = useSoundStore((s) => s.music);
-  const toggleMusic = useSoundStore((s) => s.toggleMusic);
   const { t } = useI18n();
   if (!profile) return null;
 
@@ -54,21 +51,6 @@ export function TopBar() {
       </button>
 
       <div className="flex items-center gap-1 shrink-0">
-        <button
-          onClick={toggleMusic}
-          className="glass rounded-full p-1.5 hover:bg-navy-800/80 transition"
-          title={t("settings.music")}
-          aria-label={t("settings.music")}
-        >
-          {music ? (
-            <Music className="size-4 text-gold-400" />
-          ) : (
-            <span className="relative grid place-items-center">
-              <Music className="size-4 text-cream/40" />
-              <span className="absolute block h-0.5 w-5 rotate-45 rounded bg-rose-400" />
-            </span>
-          )}
-        </button>
         <button
           onClick={() => go("notifications")}
           className="glass rounded-full p-2 hover:bg-navy-800/80 transition relative"