refactor: unify desktop apps and Settings under item catalog

template/docs/gui-apps.md

@@ -841,18 +841,36 @@ External standalone apps can be discovered by the desktop through TOML manifest
 
 ```toml
 [app]
+id = "my-app"
 name = "My App"
-binary = "myapp"
+binary = "myapp.elf"
 icon = "myapp_icon.svg"
 
 [menu]
 category = "Applications"
 visible = true
+
+[desktop]
+section = "apps"
+admin_only = false
+
+[launch]
+pass_home_dir = true
 ```
 
 **Categories:** `Applications`, `Internet`, `System`, `Games`
 
-The desktop scans `0:/apps/` at startup and adds matching entries to the application menu. The `binary` field is the executable name (looked up in the system path).
+The desktop scans `0:/apps/` at startup and builds one catalog used by the
+application menu, launcher search, and the Apps and Settings virtual folders.
+`app.id` must be unique; when omitted, the containing directory name is used.
+The `binary` field names an executable in that app's bundle.
+
+`desktop.section` accepts `apps` (the default), `settings`, or `hidden`.
+Section placement is independent of `menu.visible`: a Settings item can be
+hidden from the application menu while remaining directly searchable in the
+launcher. Set `desktop.admin_only` to hide the item from non-administrator
+users. `launch.pass_home_dir` controls whether the current user's home path is
+passed as the executable's first argument.
 
 ---