Harden rate limit by using server-trusted IP address

Update rate limiting logic to use the server's IP address (extracted from request headers or socket) instead of the client-provided visitorId to prevent spoofing.

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artifacts/api-server/src/routes/events.ts

@@ -297,9 +297,10 @@ export function attachWebSocketServer(server: Server): void {
           // Broadcast visitor message to all watchers
           broadcastToAll(wss, { type: "chat", agentId: "visitor", text });
 
-          // Rate-limit Timmy's AI replies per visitor
-          const visId = String(msg.visitorId ?? ip);
-          if (!checkChatRateLimit(visId)) {
+          // Rate-limit Timmy's AI replies — key on server-trusted IP, not
+          // client-provided visitorId (which is trivially spoofable).
+          const ipStr = Array.isArray(ip) ? (ip[0] ?? "unknown") : String(ip).split(",")[0]!.trim();
+          if (!checkChatRateLimit(ipStr)) {
             send(socket, {
               type: "chat",
               agentId: "timmy",