feat: context menus on search panel, track info dialog, separate shuffle buttons

- Add right-click context menus to search panel tracks (play, queue,
  favorites, playlist, go to album/artist, track info) and albums
  (open, favorite, go to artist)
- Add "Track info..." dialog showing metadata (title, performer,
  composer, album, quality, hi-res status) — available everywhere:
  playlists, albums, favorites, search results
- Split artist page shuffle into "Shuffle" (popular tracks) and
  "Shuffle All" (deep shuffle across all releases)
- Remove magnifying glass emoji from welcome text

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

src/list/tracks.cpp

@@ -1,5 +1,6 @@
 #include "tracks.hpp"
 #include "../util/settings.hpp"
+#include "../util/trackinfo.hpp"
 
 #include <QHeaderView>
 #include <QMenu>
@@ -237,6 +238,13 @@ void Tracks::onContextMenu(const QPoint &pos)
         }
     }
 
+    // Track info
+    menu.addSeparator();
+    auto *infoAction = menu.addAction(tr("Track info..."));
+    connect(infoAction, &QAction::triggered, this, [this, trackJson] {
+        TrackInfoDialog::show(trackJson, this);
+    });
+
     menu.exec(viewport()->mapToGlobal(pos));
 }