v0.18.2 resume rotated files instead of replay, keep quiet SSE alive, refuse HEAD on strem path

internal/core/const.go

@@ -13,6 +13,10 @@ const (
 
 	SessionCleanupInterval = 5 * time.Minute
 
+	// Idle keepalive for a served stream. Well under SessionDefaultMaxIdleTime,
+	// so a quiet stream refreshes its session long before the sweep expires it.
+	StreamKeepaliveInterval = 15 * time.Second
+
 	ServiceStatsUpdateInterval = 1 * time.Second
 
 	ShutdownTimeout = 10 * time.Second