feat: change theme and index style

web/src/store/theme.js

@@ -0,0 +1,15 @@
+// src/store/index.js
+import { defineStore } from "pinia";
+
+export const useThemeStore = defineStore("theme", {
+  state: () => ({
+    theme: localStorage.getItem("theme") || "light" // 默认从 localStorage 获取主题
+  }),
+  actions: {
+    setTheme(theme) {
+      this.theme = theme;
+      document.documentElement.setAttribute("data-theme", theme);
+      localStorage.setItem("theme", theme); // 保存到 localStorage
+    }
+  }
+});