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/view/queuepanel.cpp

@@ -173,7 +173,9 @@ void QueuePanel::refresh()
 
     for (int i = 0; i < upcoming.size(); ++i) {
         const QJsonObject &t = upcoming.at(i);
-        const QString title  = t["title"].toString();
+        const QString base    = t["title"].toString();
+        const QString ver     = t["version"].toString().trimmed();
+        const QString title   = ver.isEmpty() ? base : base + QStringLiteral(" (") + ver + QLatin1Char(')');
         const QString artist = t["performer"].toObject()["name"].toString().isEmpty()
             ? t["album"].toObject()["artist"].toObject()["name"].toString()
             : t["performer"].toObject()["name"].toString();