Song handling simplification

Add languge field to songs

Add lyric display

SongItem.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <QString>
+#include <QRandomGenerator>
+#include <cstdint>
+
+class SongItem {
+public:
+    QString caption;
+    QString lyrics;
+    uint64_t uniqueId; // Unique identifier for tracking across playlist changes
+    QString file;
+    QString vocalLanguage; // Language override for vocal generation (ISO 639 code or empty)
+
+    inline SongItem(const QString &caption = "", const QString &lyrics = "")
+        : caption(caption), lyrics(lyrics) {
+        // Generate a unique ID using cryptographically secure random number
+        uniqueId = QRandomGenerator::global()->generate64();
+    }
+};