完善初始化更新

sproutgate-frontend/src/components/SplashScreen.jsx

@@ -0,0 +1,27 @@
+import React from "react";
+import { LOGO_192_SRC } from "../config";
+
+export default function SplashScreen() {
+  return (
+    <div className="splash">
+      <div className="splash-glow" aria-hidden="true" />
+      <div className="splash-content">
+        <div className="splash-logo-wrap">
+          <div className="splash-rings" aria-hidden="true">
+            <span />
+            <span />
+            <span />
+          </div>
+          <img className="splash-logo" src={LOGO_192_SRC} alt="SproutGate" width={120} height={120} decoding="async" />
+        </div>
+        <div className="splash-title">萌芽账户认证中心</div>
+        <div className="splash-subtitle">加载中</div>
+        <div className="splash-dots" aria-label="加载中">
+          <span />
+          <span />
+          <span />
+        </div>
+      </div>
+    </div>
+  );
+}