musrview is a plain executable, hence on macOS it showed up with the generic
'exec' icon. The QApplication behind the embedded display is created by ROOT,
musrview now sets its name and icon after the first window is shown (needs
Qt6::Widgets, the same Qt ROOT's qt6web links against).
- new application icon src/musrview_web/musrview.svg/.png, installed next to
musrview.html and found the same way (PMusrWebCanvas::WebDir())
- macOS: an Info.plist embedded into the binary gives name and bundle id
- Linux: musrview.desktop plus hicolor icons, and setDesktopFileName() so that
Wayland compositors can match the window to its icon
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>