style(titlebar): theme-independent traffic-lights + song pill

Window controls use fixed macOS-style colored dots (red/yellow/green)
so they stay visible on every theme (broke on Middle-Earth etc. where
text tokens collapsed against the sidebar bg). Song indicator becomes
a dark translucent pill with light text + text-shadow for universal
contrast. Removed the "Psysonic" label — the sidebar logo already
covers it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/TitleBar.tsx

@@ -10,8 +10,6 @@ export default function TitleBar() {
 
   return (
     <div className="titlebar" data-tauri-drag-region>
-      <span className="titlebar-title" data-tauri-drag-region>Psysonic</span>
-
       <div className="titlebar-track" data-tauri-drag-region>
         {currentTrack && (
           <>