func (w *response) disableWriteContinue() {
	w.writeContinueMu.Lock()
	w.canWriteContinue.Store(false)
	w.writeContinueMu.Unlock()
}

// writerOnly hides an io.Writer value's optional ReadFrom method
// from io.Copy.
type writerOnly struct {
	io.Writer
}

// ReadFrom is here to optimize copying from an [*os.File] regular file
// to a [*net.TCPConn] with sendfile, or from a supported src type such