优化：getSiteInfo、statistics使用了状态管理模式，提升性能。

src/utils/type-guards.ts

@@ -0,0 +1,105 @@
+/**
+ * 类型保护工具函数
+ */
+
+/**
+ * 检查值是否为有效的数字
+ */
+export function isValidNumber(value: unknown): value is number {
+  return typeof value === 'number' && !isNaN(value) && isFinite(value);
+}
+
+/**
+ * 检查值是否为有效的字符串
+ */
+export function isValidString(value: unknown): value is string {
+  return typeof value === 'string' && value.length > 0;
+}
+
+/**
+ * 检查对象是否有有效的 ID
+ */
+export function hasValidId(obj: unknown): obj is { id: number } {
+  return (
+    typeof obj === 'object' &&
+    obj !== null &&
+    'id' in obj &&
+    isValidNumber((obj as any).id)
+  );
+}
+
+/**
+ * 安全获取数字值，提供默认值
+ */
+export function safeNumber(value: unknown, defaultValue = 0): number {
+  if (isValidNumber(value)) {
+    return value;
+  }
+  if (typeof value === 'string') {
+    const parsed = Number(value);
+    return isValidNumber(parsed) ? parsed : defaultValue;
+  }
+  return defaultValue;
+}
+
+/**
+ * 安全获取字符串值，提供默认值
+ */
+export function safeString(value: unknown, defaultValue = ''): string {
+  return typeof value === 'string' ? value : defaultValue;
+}
+
+/**
+ * 检查 API 响应是否有效
+ */
+export function isValidApiResponse<T>(response: unknown): response is { count: number; list?: T[] } {
+  return (
+    typeof response === 'object' &&
+    response !== null &&
+    'count' in response &&
+    isValidNumber((response as any).count)
+  );
+}
+
+/**
+ * 检查统计数据是否有效
+ */
+export function isValidStatistics(data: unknown): data is {
+  id?: number;
+  userCount?: number;
+  orderCount?: number;
+  totalSales?: number;
+} {
+  return (
+    typeof data === 'object' &&
+    data !== null
+  );
+}
+
+/**
+ * 安全的对象合并，过滤掉 undefined 值
+ */
+export function safeMerge<T extends Record<string, any>>(
+  target: T,
+  source: Partial<T>
+): T {
+  const result = { ...target };
+  
+  for (const [key, value] of Object.entries(source)) {
+    if (value !== undefined) {
+      result[key as keyof T] = value;
+    }
+  }
+  
+  return result;
+}
+
+/**
+ * 创建带有默认值的对象
+ */
+export function withDefaults<T extends Record<string, any>>(
+  data: Partial<T>,
+  defaults: T
+): T {
+  return safeMerge(defaults, data);
+}