Initial implementation of qobuz-qt

- Rust backend (qobuz-backend static lib): Qobuz API client (reqwest/tokio),
  Symphonia audio decoder, CPAL audio output, extern "C" FFI bridge
- Qt 6 frontend mirroring spotify-qt layout: toolbar with playback controls,
  left library dock, central track list, right search panel
- Auth: email/password login with MD5-signed requests; session token persisted
  via QSettings
- Playback: double-click a track → Rust fetches stream URL → Symphonia decodes
  → CPAL outputs to default audio device
- Dark Fusion palette matching spotify-qt feel

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

src/model/tracklistmodel.cpp

@@ -0,0 +1,113 @@
+#include "tracklistmodel.hpp"
+
+#include <QJsonValue>
+#include <QColor>
+
+TrackListModel::TrackListModel(QObject *parent)
+    : QAbstractTableModel(parent)
+{}
+
+void TrackListModel::setTracks(const QJsonArray &tracks)
+{
+    beginResetModel();
+    m_tracks.clear();
+    m_tracks.reserve(tracks.size());
+
+    for (const QJsonValue &v : tracks) {
+        const QJsonObject t = v.toObject();
+        TrackItem item;
+        item.id         = static_cast<qint64>(t["id"].toDouble());
+        item.number     = t["track_number"].toInt();
+        item.title      = t["title"].toString();
+        item.duration   = static_cast<qint64>(t["duration"].toDouble());
+        item.hiRes      = t["hires_streamable"].toBool();
+        item.streamable = t["streamable"].toBool();
+        item.raw        = t;
+
+        // Performer / artist
+        const QJsonObject performer = t["performer"].toObject();
+        item.artist = performer["name"].toString();
+        if (item.artist.isEmpty()) {
+            const QJsonObject album = t["album"].toObject();
+            const QJsonObject artist = album["artist"].toObject();
+            item.artist = artist["name"].toString();
+        }
+
+        // Album
+        const QJsonObject album = t["album"].toObject();
+        item.album  = album["title"].toString();
+        item.albumId = album["id"].toString();
+
+        m_tracks.append(item);
+    }
+    endResetModel();
+}
+
+void TrackListModel::clear()
+{
+    beginResetModel();
+    m_tracks.clear();
+    endResetModel();
+}
+
+int TrackListModel::rowCount(const QModelIndex &parent) const
+{
+    if (parent.isValid()) return 0;
+    return m_tracks.size();
+}
+
+int TrackListModel::columnCount(const QModelIndex &parent) const
+{
+    if (parent.isValid()) return 0;
+    return ColCount;
+}
+
+QVariant TrackListModel::data(const QModelIndex &index, int role) const
+{
+    if (!index.isValid() || index.row() >= m_tracks.size())
+        return {};
+
+    const TrackItem &t = m_tracks.at(index.row());
+
+    if (role == Qt::DisplayRole) {
+        switch (index.column()) {
+        case ColNumber:   return t.number > 0 ? QString::number(t.number) : QString();
+        case ColTitle:    return t.title;
+        case ColArtist:   return t.artist;
+        case ColAlbum:    return t.album;
+        case ColDuration: return formatDuration(t.duration);
+        }
+    }
+
+    if (role == Qt::ForegroundRole && !t.streamable) {
+        return QColor(Qt::gray);
+    }
+
+    if (role == TrackIdRole)   return t.id;
+    if (role == TrackJsonRole) return t.raw;
+    if (role == HiResRole)     return t.hiRes;
+
+    return {};
+}
+
+QVariant TrackListModel::headerData(int section, Qt::Orientation orientation, int role) const
+{
+    if (orientation != Qt::Horizontal || role != Qt::DisplayRole)
+        return {};
+
+    switch (section) {
+    case ColNumber:   return tr("#");
+    case ColTitle:    return tr("Title");
+    case ColArtist:   return tr("Artist");
+    case ColAlbum:    return tr("Album");
+    case ColDuration: return tr("Duration");
+    }
+    return {};
+}
+
+QString TrackListModel::formatDuration(qint64 secs)
+{
+    const int m = static_cast<int>(secs / 60);
+    const int s = static_cast<int>(secs % 60);
+    return QStringLiteral("%1:%2").arg(m).arg(s, 2, 10, QLatin1Char('0'));
+}