AdminStealth 0.3.12: keep hidden admins off the team select screen

Hidden admins skip the team screen on reconnect (moved to spectators until re-hidden), never
receive the server's team menu message, and a pick from the screen M opens is answered by
telling only their client they joined spectators. The restore runs css_hide at most once, since
it toggles. Each command listener gets its own delegate: CSS keys listeners by handler, and
reusing one orphaned the first registration, which then swallowed its command.

README.md

@@ -15,6 +15,17 @@ admin off the scoreboard. This plugin makes it look like they left the server:
 - A hidden admin can't join a team or go to spectators (`jointeam` and `spectate` are blocked
   with a chat message). If the game or another plugin puts them on a team anyway, which makes
   SimpleAdmin unhide them, they're hidden again straight away.
+- On reconnect or map change, a hidden admin is moved to spectators 0.1 s after connecting, so
+  the team select screen doesn't open, until the restore hides them again.
+- The team select screen: the server's "team" menu message (`CS_UM_VGUIMenu`) is never sent to
+  a hidden admin. M opens it on the client regardless, and a player with no team can't close it
+  without picking, so a pick is answered by telling only that client it joined spectators
+  (with `sv_disable_teamselect_menu` on around it); nobody else sees a team change.
+- Restoring runs `css_hide` at most once: it toggles, so a second run could unhide them.
+
+Needs our SimpleAdmin fork (1.8.2b-zio2 or later), where moving to spectators doesn't unhide a
+hidden admin. Never hot-reload CS2-SimpleAdmin while this runs: CSS keeps handing out the old
+instance's API until the server restarts.
 - `status` from a player's console is blocked and prints nothing. It still works from the server
   console and RCON.
 
@@ -37,8 +48,8 @@ the `status` block works.
 - Unhiding doesn't announce the admin as joining again.
 - The server browser and trackers get the player list from a separate server query, which this
   doesn't touch, so they still list a hidden admin.
-- Reloading CS2-SimpleAdmin on its own leaves this plugin listening to the old instance. Reload
-  AdminStealth after it.
+- Reloading CS2-SimpleAdmin on its own leaves this plugin (and WebPanelBridge) talking to the old
+  instance until a server restart.
 
 ## Install