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/list-add.svg

@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 22 22">
+  <defs id="defs3051">
+    <style type="text/css" id="current-color-scheme">
+      .ColorScheme-Text {
+        color:#eff0f1;
+      }
+      </style>
+  </defs>
+ <path 
+    style="fill:currentColor;fill-opacity:1;stroke:none" 
+    d="M 10 4 L 10 11 L 3 11 L 3 12 L 10 12 L 10 19 L 11 19 L 11 12 L 18 12 L 18 11 L 11 11 L 11 4 L 10 4 z "
+    class="ColorScheme-Text"
+    />  
+</svg>