feat: artist/page endpoint, multi-disc fix, playlist ownership, UX improvements

- Switch artist view to artist/page API (proper sections: Albums, Singles & EPs,
  Live, Compilations; version in titles like "Deluxe")
- Fix artist sections categorization using releases[].type from artist/page
- Add getUser() backend call; fetch on session restore when userId=0 to fix
  playlist ownership (Remove from playlist / Delete playlist were missing)
- Fix multi-disc double-click / Play Now queue start index (disc headers were
  counted in row index but excluded from currentTracksJson)
- Hide redundant Album column when viewing an album
- Make artist name in context header clickable (navigates to artist page)
- Fix gap between title and artist name in context header (addStretch)
- Fix queue panel track titles to include version field
- Fix album list to show version in title column

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/model/tracklistmodel.cpp

@@ -17,17 +17,27 @@ void TrackListModel::setTracks(const QJsonArray &tracks,
     m_tracks.clear();
     m_tracks.reserve(tracks.size());
 
+    // Parse into a temporary list first so we can detect multi-disc
+    QVector<TrackItem> parsed;
+    parsed.reserve(tracks.size());
+
     int seq = 1;
     for (const QJsonValue &v : tracks) {
         const QJsonObject t = v.toObject();
         TrackItem item;
         item.id               = static_cast<qint64>(t["id"].toDouble());
         item.playlistTrackId  = static_cast<qint64>(t["playlist_track_id"].toDouble());
-        item.title            = t["title"].toString();
+        item.discNumber       = t["media_number"].toInt(1);
         item.duration         = static_cast<qint64>(t["duration"].toDouble());
-        item.hiRes      = t["hires_streamable"].toBool();
-        item.streamable = t["streamable"].toBool(true);
-        item.raw        = t;
+        item.streamable       = t["streamable"].toBool(true);
+        item.hiRes            = t["hires_streamable"].toBool();
+        item.raw              = t;
+
+        // Combine title + version ("Melody" + "Vocal Remix" → "Melody (Vocal Remix)")
+        const QString base    = t["title"].toString();
+        const QString version = t["version"].toString().trimmed();
+        item.title = version.isEmpty() ? base
+                   : base + QStringLiteral(" (") + version + QLatin1Char(')');
 
         if (useSequential) {
             item.number = seq++;
@@ -48,17 +58,46 @@ void TrackListModel::setTracks(const QJsonArray &tracks,
         item.album   = album["title"].toString();
         item.albumId = album["id"].toString();
 
-        m_tracks.append(item);
+        parsed.append(item);
     }
 
-    // Re-apply sort silently inside the reset (no layout signals needed here)
-    if (m_sortColumn >= 0)
-        sortData(m_sortColumn, m_sortOrder);
+    // Multi-disc only makes sense for album context (not playlists / fav / search)
+    int maxDisc = 1;
+    if (!usePosition && !useSequential) {
+        for (const TrackItem &t : parsed)
+            maxDisc = qMax(maxDisc, t.discNumber);
+    }
+    m_hasMultipleDiscs = (maxDisc > 1);
+
+    if (m_hasMultipleDiscs) {
+        // Sort by disc then track number
+        std::stable_sort(parsed.begin(), parsed.end(), [](const TrackItem &a, const TrackItem &b) {
+            return a.discNumber != b.discNumber ? a.discNumber < b.discNumber
+                                               : a.number < b.number;
+        });
+        // Interleave disc header items
+        int currentDisc = -1;
+        for (const TrackItem &t : parsed) {
+            if (t.discNumber != currentDisc) {
+                TrackItem header;
+                header.isDiscHeader = true;
+                header.discNumber   = t.discNumber;
+                header.title        = tr("Disc %1").arg(t.discNumber);
+                m_tracks.append(header);
+                currentDisc = t.discNumber;
+            }
+            m_tracks.append(t);
+        }
+    } else {
+        m_tracks = parsed;
+        // Re-apply sort silently inside the reset
+        if (m_sortColumn >= 0)
+            sortData(m_sortColumn, m_sortOrder);
+    }
 
     endResetModel();
 
-    // Tell external listeners the sorted order is ready (e.g. PlayQueue sync)
-    if (m_sortColumn >= 0)
+    if (!m_hasMultipleDiscs && m_sortColumn >= 0)
         emit sortApplied();
 }
 
@@ -115,6 +154,23 @@ void TrackListModel::setPlayingId(qint64 id)
                          {Qt::FontRole, Qt::DecorationRole});
 }
 
+Qt::ItemFlags TrackListModel::flags(const QModelIndex &index) const
+{
+    if (!index.isValid() || index.row() >= m_tracks.size())
+        return Qt::NoItemFlags;
+    if (m_tracks.at(index.row()).isDiscHeader)
+        return Qt::ItemIsEnabled;
+    return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
+}
+
+QVector<int> TrackListModel::discHeaderRows() const
+{
+    QVector<int> rows;
+    for (int i = 0; i < m_tracks.size(); ++i)
+        if (m_tracks[i].isDiscHeader) rows.append(i);
+    return rows;
+}
+
 int TrackListModel::rowCount(const QModelIndex &parent) const
 {
     return parent.isValid() ? 0 : m_tracks.size();
@@ -131,6 +187,19 @@ QVariant TrackListModel::data(const QModelIndex &index, int role) const
         return {};
 
     const TrackItem &t = m_tracks.at(index.row());
+
+    // Disc header rows: styled separator spanning all columns via setFirstColumnSpanned
+    if (t.isDiscHeader) {
+        if (role == Qt::DisplayRole && index.column() == ColNumber)
+            return t.title;
+        if (role == Qt::FontRole) {
+            QFont f; f.setBold(true); return f;
+        }
+        if (role == Qt::ForegroundRole)
+            return QColor(0xFF, 0xB2, 0x32);
+        return {};
+    }
+
     const bool isPlaying = (t.id == m_playingId && m_playingId != 0);
 
     if (role == Qt::DisplayRole) {
@@ -213,7 +282,8 @@ void TrackListModel::sort(int column, Qt::SortOrder order)
     m_sortColumn = column;
     m_sortOrder  = order;
 
-    if (m_tracks.isEmpty()) return;
+    // Multi-disc albums keep their disc-ordered layout; don't re-sort
+    if (m_hasMultipleDiscs || m_tracks.isEmpty()) return;
 
     emit layoutAboutToBeChanged();
     sortData(column, order);