feat: The Steamify shortcut opens the app

Steamify CachyOS on the desktop and in the launcher starts the newest app
(in Konsole the first time, while PySide6 still has to be installed); the
terminal menu is Steamify Terminal in the launcher. A shortcut from before
2.0.1 is ticked in the menu, so a normal run replaces it. steamify-app.sh
leaves the shortcut's launcher entry (same id) alone.

README.md

@@ -25,8 +25,9 @@ Steam Machine.
    KDE wallet password prompts (e.g. from Brave). Typing a password with a
    controller is no fun
    ([details](TECHNICAL.md#single-user-mode-sddm-no-locking)).
-5. **Steamify shortcut** - an icon on the desktop and in the launcher that
-   opens the newest Steamify, so you don't need the install command again.
+5. **Steamify shortcut** - "Steamify CachyOS" on the desktop and in the
+   launcher opens the newest Steamify app, so you don't need the install
+   command again. "Steamify Terminal" in the launcher opens the terminal menu.
 6. **HDMI-CEC** (experimental; off by default, on by default on a Steam
    Machine) - use Steam with your TV's
    remote, and the TV turns on and off with the PC. Needs a PC with CEC (like