chore(config): update vitest config, add vercel.json and manifest

- Update vitest.config.ts

- Add vercel.json for deployment configuration

- Add PWA manifest

src/app/manifest.ts

@@ -0,0 +1,21 @@
+import type { MetadataRoute } from "next";
+
+export default function manifest(): MetadataRoute.Manifest {
+  return {
+    name: "Next_Edu - K12 智慧教务系统",
+    short_name: "NextEdu",
+    description: "Enterprise Grade K12 Education Management System",
+    start_url: "/",
+    display: "standalone",
+    background_color: "#ffffff",
+    theme_color: "#1976d2",
+    orientation: "any",
+    icons: [
+      {
+        src: "/icon.svg",
+        sizes: "any",
+        type: "image/svg+xml",
+      },
+    ],
+  };
+}