Implement comprehensive WebSocket subscription stability fixes

- Resolved critical issues causing subscriptions to drop after 30-60 seconds due to unconsumed receiver channels.
- Introduced per-subscription consumer goroutines to ensure continuous event delivery and prevent channel overflow.
- Enhanced REQ parsing to handle both wrapped and unwrapped filter arrays, eliminating EOF errors.
- Updated publisher logic to correctly send events to receiver channels, ensuring proper event delivery to subscribers.
- Added extensive documentation and testing tools to verify subscription stability and performance.
- Bumped version to v0.26.2 to reflect these significant improvements.

app/handle-close.go

@@ -23,13 +23,30 @@ func (l *Listener) HandleClose(req []byte) (err error) {
 	if len(env.ID) == 0 {
 		return errors.New("CLOSE has no <id>")
 	}
+
+	subID := string(env.ID)
+
+	// Cancel the subscription goroutine by calling its cancel function
+	l.subscriptionsMu.Lock()
+	if cancelFunc, exists := l.subscriptions[subID]; exists {
+		log.D.F("cancelling subscription %s for %s", subID, l.remote)
+		cancelFunc()
+		delete(l.subscriptions, subID)
+	} else {
+		log.D.F("subscription %s not found for %s (already closed?)", subID, l.remote)
+	}
+	l.subscriptionsMu.Unlock()
+
+	// Also remove from publisher's tracking
 	l.publishers.Receive(
 		&W{
 			Cancel: true,
 			remote: l.remote,
 			Conn:   l.conn,
-			Id:     string(env.ID),
+			Id:     subID,
 		},
 	)
+
+	log.D.F("CLOSE processed for subscription %s @ %s", subID, l.remote)
 	return
 }