feat: add album favorites in header and unify browse controls

Improve album workflow with in-header favorite toggle, keep favorite state synced from backend, and normalize browse top-bar sizing while increasing audio output buffer headroom to reduce glitches.

src/mainwindow.hpp

@@ -55,7 +55,9 @@ private:
     QobuzBackend    *m_backend     = nullptr;
     PlayQueue       *m_queue       = nullptr;
     QVector<QPair<qint64, QString>> m_userPlaylists;
+    QSet<QString> m_favAlbumIds;
     QSet<qint64> m_favArtistIds;
+    bool m_showFavAlbumsOnLoad = false;
     bool m_showFavArtistsOnLoad = false;
     MainToolBar     *m_toolBar     = nullptr;
     MainContent     *m_content     = nullptr;