feat: album list, artist list, and artist detail views

- Fav albums: now shows a sortable list (title/artist/year/tracks);
  double-click opens the album
- Fav artists: now shows a sortable list; double-click opens the artist
- Artist detail page: name, biography summary, and their album list
- Rust ArtistDto gains albums field; get_artist fixed to extra=albums only
- Volume popup minimum width set so "100%" label is never clipped

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

src/view/artistlistview.hpp

@@ -0,0 +1,53 @@
+#pragma once
+
+#include <QTreeWidget>
+#include <QTreeWidgetItem>
+#include <QHeaderView>
+#include <QJsonObject>
+#include <QJsonArray>
+
+/// A simple list of artists.
+/// Double-clicking an item emits artistSelected(artistId).
+class ArtistListView : public QTreeWidget
+{
+    Q_OBJECT
+
+public:
+    explicit ArtistListView(QWidget *parent = nullptr) : QTreeWidget(parent)
+    {
+        setColumnCount(2);
+        setHeaderLabels({tr("Artist"), tr("Albums")});
+        setRootIsDecorated(false);
+        setAlternatingRowColors(true);
+        setSelectionBehavior(QAbstractItemView::SelectRows);
+
+        header()->setStretchLastSection(false);
+        header()->setSectionResizeMode(0, QHeaderView::Stretch);
+        header()->setSectionResizeMode(1, QHeaderView::ResizeToContents);
+
+        connect(this, &QTreeWidget::itemDoubleClicked,
+                this, [this](QTreeWidgetItem *item, int) {
+            const qint64 id = item->data(0, Qt::UserRole).toLongLong();
+            if (id > 0) emit artistSelected(id);
+        });
+    }
+
+    void setArtists(const QJsonArray &artists)
+    {
+        clear();
+        for (const auto &v : artists) {
+            const QJsonObject a = v.toObject();
+            const qint64 id     = static_cast<qint64>(a["id"].toDouble());
+            const QString name  = a["name"].toString();
+            const int albums    = a["albums_count"].toInt();
+
+            auto *item = new QTreeWidgetItem(this);
+            item->setText(0, name);
+            item->setText(1, albums > 0 ? QString::number(albums) : QString());
+            item->setData(0, Qt::UserRole, id);
+        }
+    }
+
+signals:
+    void artistSelected(qint64 artistId);
+};