feat(auth): 添加用户认证模块与登录页面

src/styles/css/transition.css

@@ -0,0 +1,9 @@
+.fade-enter-active,
+.fade-leave-active {
+  transition: opacity 0.25s ease-in-out;
+}
+
+.fade-enter-from,
+.fade-leave-to {
+  opacity: 0;
+}