feat: initial qobuz-qt source

Lightweight Qt6 desktop client for Qobuz with a Rust audio backend
(Symphonia/CPAL via staticlib FFI). Mirrors the spotify-qt layout:
toolbar with playback controls, library/context docks on the left,
tabbed search side panel on the right, queue panel, now-playing dock.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

res/icons/media-playlist-append.svg

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+  <defs id="defs3051">
+    <style type="text/css" id="current-color-scheme">
+      .ColorScheme-Text {
+        color:#eff0f1;
+      }
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+  </defs>
+ <path 
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+    />  
+</svg>