fix: Always prefer local cards if available (#5762)

* Try to better reproduce pre-provider ID behavior

If "override all card art with personal preference" setting is set, look
for custom art for all sets instead of just the most preferred set.

* Warning when using both custom art and the printing selector

* QDirIterator::nextFileInfo is Qt 6.3+

* Translation

cockatrice/src/client/ui/picture_loader/picture_loader.cpp

@@ -195,3 +195,31 @@ void PictureLoader::picsPathChanged()
 {
     QPixmapCache::clear();
 }
+
+bool PictureLoader::hasCustomArt()
+{
+    auto picsPath = SettingsCache::instance().getPicsPath();
+    QDirIterator it(picsPath, QDir::Dirs | QDir::NoDotAndDotDot);
+
+    // Check if there is at least one non-directory file in the pics path, other
+    // than in the "downloadedPics" subdirectory.
+    while (it.hasNext()) {
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 3, 0))
+        QFileInfo dir(it.nextFileInfo());
+#else
+        // nextFileInfo() is only available in Qt 6.3+, for previous versions, we build
+        // the QFileInfo from a QString which requires more system calls.
+        QFileInfo dir(it.next());
+#endif
+
+        if (it.fileName() == "downloadedPics")
+            continue;
+
+        QDirIterator subIt(it.filePath(), QDir::Files, QDirIterator::Subdirectories | QDirIterator::FollowSymlinks);
+        if (subIt.hasNext()) {
+            return true;
+        }
+    }
+
+    return false;
+}