improve reverse proxy and serverhandling

- buffer pool for IO copy
  - flush response after read, now works with event stream
  - fixed error handling for server

internal/net/http/server/error.go

@@ -8,11 +8,11 @@ import (
 	"github.com/rs/zerolog"
 )
 
-func HandleError(logger *zerolog.Logger, err error) {
+func HandleError(logger *zerolog.Logger, err error, msg string) {
 	switch {
 	case err == nil, errors.Is(err, http.ErrServerClosed), errors.Is(err, context.Canceled):
 		return
 	default:
-		logger.Fatal().Err(err).Msg("server error")
+		logger.Fatal().Err(err).Msg(msg)
 	}
 }