feat: add cookie utility functions for client-side cookie management

.vitepress/theme/utils/cookie.ts

@@ -0,0 +1,50 @@
+/**
+ * 设置 Cookie
+ * @param name - Cookie 名称
+ * @param value - Cookie 值
+ * @param days - 过期天数（可选，默认 365 天）
+ */
+export function setCookie(name: string, value: string, days: number = 365): void {
+  if (typeof document === "undefined") return;
+
+  let expires = "";
+  if (days) {
+    const date = new Date();
+    date.setTime(date.getTime() + days * 24 * 60 * 60 * 1000);
+    expires = "; expires=" + date.toUTCString();
+  }
+
+  document.cookie = name + "=" + encodeURIComponent(value) + expires + "; path=/";
+}
+
+/**
+ * 获取 Cookie
+ * @param name - Cookie 名称
+ * @returns Cookie 值，如果不存在则返回 null
+ */
+export function getCookie(name: string): string | null {
+  if (typeof document === "undefined") return null;
+
+  const nameEQ = name + "=";
+  const ca = document.cookie.split(";");
+
+  for (let i = 0; i < ca.length; i++) {
+    let c = ca[i];
+    while (c.charAt(0) === " ") {
+      c = c.substring(1, c.length);
+    }
+    if (c.indexOf(nameEQ) === 0) {
+      return decodeURIComponent(c.substring(nameEQ.length, c.length));
+    }
+  }
+
+  return null;
+}
+
+/**
+ * 删除 Cookie
+ * @param name - Cookie 名称
+ */
+export function deleteCookie(name: string): void {
+  setCookie(name, "", -1);
+}