feat(desktop,server,web): app icons, completion notifications, single-user mode, bundled penguin CLI (#226)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/docs/content/server-api.en.md

@@ -67,6 +67,8 @@ curl -c cookies.txt -H "Content-Type: application/json" \
 | POST | /api/admin/users/:userId/password | Reset a password (invalidates all of that user's login sessions) |
 | DELETE | /api/admin/users/:userId | Delete a user |
 
+In desktop mode (the server spawned by the desktop app) the whole surface answers `403` with code `desktop_single_user`: the desktop app is single-user, so user management is disabled — existing users in the data root are untouched.
+
 ### Server Settings (admin only)
 
 | Method | Path | Description |
@@ -97,7 +99,7 @@ curl -c cookies.txt -H "Content-Type: application/json" \
 | POST | /api/projects/:projectId/members | Add a member: `{userId}` |
 | DELETE | /api/projects/:projectId/members/:userId | Remove a member |
 
-Member writes are owner-only.
+Member writes are owner-only. The member routes also answer `403 desktop_single_user` in desktop mode (see User Administration above).
 
 ### Models