Security added on delete service and list all node + cleaning some code

backend/models/login.go

@@ -0,0 +1,11 @@
+package models
+
+type LoginRequest struct {
+	Username string `json:"username"`
+	Password string `json:"password"`
+}
+
+type LoginResponse struct {
+	Message string `json:"message"`
+	Role    string `json:"role"`
+}