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/data-warning.svg

@@ -0,0 +1,9 @@
+<svg version="1.1" viewBox="0 0 22 22" xmlns="http://www.w3.org/2000/svg">
+    <style type="text/css" id="current-color-scheme">
+        .ColorScheme-NeutralText {
+            color:#f67400;
+        }
+    </style>
+    <path class="ColorScheme-NeutralText" d="m11.006318 3.0000261a0.72728737 0.72727154 0 0 0-0.65674 0.4021811l-7.2728738 14.545431a0.72728737 0.72727154 0 0 0 0.6509222 1.052362h14.545748a0.72728737 0.72727154 0 0 0 0.650922-1.052362l-7.272874-14.545431a0.72728737 0.72727154 0 0 0-0.645104-0.4021811z" fill="currentColor"/>
+    <path d="m10 7v6h2v-6zm0 8v2h2v-2z" fill="#fff"/>
+</svg>