fix(ui): activity Indicator switching constantly between online/offline (#5054)

When using HTTP2, setting the writeTimeout too low causes the channel to
close before the keepAlive event has a chance of beeing sent.

Signed-off-by: rca <raphael.catolino@gmail.com>
Co-authored-by: Deluan Quintão <deluan@navidrome.org>

server/events/sse.go

@@ -24,7 +24,8 @@ type Broker interface {
 
 const (
 	keepAliveFrequency = 15 * time.Second
-	writeTimeOut       = 5 * time.Second
+	// The timeout must be higher than the keepAliveFrequency, or the lack of activity will cause the channel to close.
+	writeTimeOut = keepAliveFrequency + 5*time.Second
 	bufferSize   = 1
 )