fix(launcher): harden stale-client recovery

- fail closed when X11 omits _NET_CLIENT_LIST or WM_CLASS, and recognize the
  RiotClientServices window class;
- require stale client processes to be at least 60 seconds old;
- recheck process identity before SIGTERM and SIGKILL and recheck the window
  before signalling;
- document the age and window-detection guards.

docs/TROUBLESHOOTING.md

@@ -150,13 +150,15 @@ download is restarted when recovery is enabled. Other desktop environments are
 not supported by this helper; recovery is off by default.
 
 For a live Darling runtime with no visible client window but stale Riot/League/
-CEF processes, `RCLOL_RECOVER_STALE_CLIENT=1` performs a partial recovery before
-the next launch. It keeps `darlingserver`, launchd/mldr, sockets and `.init.pid`,
-stops only the stale client process tree, and then lets the normal launcher start
-the product again. It does nothing while a game process is running or when a
-managed client window is visible. With X11/Xwayland unavailable it fails closed.
-This saves the Darling bootstrap but not the Riot Client/CEF startup itself. If
-no window appears afterward, use a full runtime shutdown/restart.
+CEF processes at least 60 seconds old, `RCLOL_RECOVER_STALE_CLIENT=1` performs a
+partial recovery before the next launch. It keeps `darlingserver`, launchd/mldr,
+sockets and `.init.pid`, stops only the stale client process tree, and then lets
+the normal launcher start the product again. It recognizes `LeagueClientUx`,
+`Riot Client` and `RiotClientServices` windows, does nothing while a game process
+is running or when a managed client window is visible, and fails closed when
+X11/Xwayland properties are missing or unreadable. This saves the Darling
+bootstrap but not the Riot Client/CEF startup itself. If no window appears
+afterward, use a full runtime shutdown/restart.
 
 ### Multiple client-in-game helpers