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/application-exit.svg

@@ -0,0 +1,13 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="22" height="22">
+    <defs id="defs3051">
+        <style type="text/css" id="current-color-scheme">
+        .ColorScheme-NegativeText {
+            color:#da4453;
+        }
+        </style>
+    </defs>
+ <path
+     style="fill:currentColor;fill-opacity:1;stroke:none"
+     class="ColorScheme-NegativeText"
+     d="m3 3v4 12h1 14 1v-1-12-3h-15-1m1 4h14v11h-14v-11m4 4v2h6v-2h-6" />
+</svg>