cfg: remove state field (use state file instead)

session/sessionfile.go

@@ -252,7 +252,6 @@ func (h *sessionHelper) cfgContent() string {
 	defer h.sess.mu.RUnlock()
 	p := h.sess.Core.GenerationParams()
 	var sb strings.Builder
-	fmt.Fprintf(&sb, "state=%s\n", h.sess.Core.State())
 	fmt.Fprintf(&sb, "backend=%s\n", h.sess.Core.BackendName())
 	fmt.Fprintf(&sb, "model=%s\n", h.sess.Core.ModelName())
 	fmt.Fprintf(&sb, "agent=%s\n", h.sess.Core.AgentName())