feat: 优化主题切换逻辑，添加浅色主题支持，更新相关样式

src/store/user.ts

@@ -14,7 +14,7 @@ export const useUserStore = defineStore("user", () => {
     userProfile: null,
   });
 
-  const isAuthenticated = computed(() => token.value !== null);
+  const isAuthenticated = computed(() => !!token.value);
 
   async function updateProfile() {
     const { data } = await safeClient(client.api.user.profile.get(), { silent: true });