feat(assets): add initial fonts and image assets

src/app/splash/components/splash-background.tsx

@@ -1,14 +1,18 @@
 "use client";
-/**
- * Splash 背景
- *
- * 原始 Dart: lib/ui/splash/widgets/splash_background.dart
- *   使用 `Assets.images.picBgHome.image(fit: BoxFit.cover)` 渲染全屏背景图。
- *
- * 当前实现：纯色 + CSS 渐变占位（待 `public/splash/bg.png` 资源到位后可切换为 `<Image>`）。
- */
+import Image from "next/image";
 import styles from "./splash-background.module.css";
 
 export function SplashBackground() {
-  return <div className={styles.bg} aria-hidden="true" />;
+  return (
+    <div className={styles.bg}>
+      <Image
+        src="/images/splash/pic-bg-home.png"
+        alt=""
+        fill
+        priority
+        sizes="100vw"
+        className={styles.image}
+      />
+    </div>
+  );
 }