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/window-maximize.svg

@@ -0,0 +1,10 @@
+<svg viewBox="0 0 22 22" xmlns="http://www.w3.org/2000/svg">
+    <style
+        type="text/css"
+        id="current-color-scheme">
+        .ColorScheme-Text {
+            color:#eff0f1;
+        }
+    </style>
+    <path d="M3.707 15L3 14.293l6.125-6.125L11 6.293l1.875 1.875L19 14.293l-.707.707-6.125-6.125L11 7.707 9.832 8.875 3.707 15" class="ColorScheme-Text" fill="currentColor"/>
+</svg>