fix: update doc arch

diagrams/tasks.puml

@@ -4,7 +4,12 @@ title Tasks and data flow
 
 rectangle "relay loop (main task)" as loop {
   card "public socket\nrecv_from" as recv
-  card "sessions:\nHashMap<client, Sender>" as map
+  card "filter\n(commands, query rate)" as filter
+}
+
+rectangle "shared state (Mutex)" as shared {
+  card "sessions:\nHashMap<client, Session>" as map
+  card "bans\n(bans.json)" as bans
 }
 
 rectangle "session task (one per client)" as st {
@@ -17,10 +22,18 @@ rectangle "heartbeat task" as hb {
   card "probe socket" as probe
 }
 
-recv --> map : lookup client
+rectangle "control API task (axum)" as ctl {
+  card "GET /sessions\nGET/PUT/DELETE /bans" as routes
+}
+
+recv --> filter
+filter --> bans : banned?
+filter --> map : lookup client
 map --> rx : try_send(packet)\n(full: drop)
 rx --> up : send
 up --> recv : recv, then public.send_to(client)
 tick --> probe : getinfo
 tick --> recv : heartbeat via public socket
+routes --> map : list ports,\ndrop a banned IP's sessions
+routes --> bans : set / lift
 @enduml