Release 2.1.0 Qt Quick desktop

[DXVSI]

Summary

• replace the legacy Widgets frontend with the Qt Quick desktop client and separate runtime
• add PASE media editing, export, replace, deletion, firmware safety, and clean-room protocol support
• add native StatusNotifierItem/DBusMenu tray integration
• fix explicit tray Quit so it terminates only the GUI and leaves the runtime active
• prepare package and AppStream metadata for 2.1.0

Verification

• local make package-check
• local packaging/scripts/check-release-contract.sh v2.1.0
• live KDE Wayland DBusMenu Quit: GUI PID, tray item, and instance socket disappear; runtime PID and org.tryx.Panorama owner remain unchanged
• Linux packages run 30713446649: Fedora 43/44, Ubuntu 24.04, Arch, and clean-runtime jobs passed