fix: stabilize seek slider and clean backend lint issues

src/view/maintoolbar.hpp

@@ -86,6 +86,9 @@ private:
     QVector<RecentTrackSeed> m_recentTracks;
     bool        m_playing = false;
     bool        m_seeking = false;
+    bool        m_seekPending = false;
+    quint64     m_pendingSeekTarget = 0;
+    qint64      m_pendingSeekStartedMs = 0;
     bool        m_fetchingAutoplay = false;
 
     void requestAutoplaySuggestions();