Desktop App Specification (REDIRECT STUB)

⚠️ This file is a redirect stub. The desktop application specification has been renumbered.

→ New canonical location: 21-desktop-app-specification.md

All inbound links to docs/frontend/desktop/06-desktop-app-specification.md remain valid for one release via this stub. Update your links to docs/frontend/desktop/21-desktop-app-specification.md in your next PR.