feat(usage): add usage stats export/import actions

src/services/api/usage.ts

@@ -7,12 +7,38 @@ import { computeKeyStats, KeyStats } from '@/utils/usage';
 
 const USAGE_TIMEOUT_MS = 60 * 1000;
 
+export interface UsageExportPayload {
+  version?: number;
+  exported_at?: string;
+  usage?: Record<string, unknown>;
+  [key: string]: unknown;
+}
+
+export interface UsageImportResponse {
+  added?: number;
+  skipped?: number;
+  total_requests?: number;
+  failed_requests?: number;
+  [key: string]: unknown;
+}
+
 export const usageApi = {
   /**
    * 获取使用统计原始数据
    */
   getUsage: () => apiClient.get('/usage', { timeout: USAGE_TIMEOUT_MS }),
 
+  /**
+   * 导出使用统计快照
+   */
+  exportUsage: () => apiClient.get<UsageExportPayload>('/usage/export', { timeout: USAGE_TIMEOUT_MS }),
+
+  /**
+   * 导入使用统计快照
+   */
+  importUsage: (payload: unknown) =>
+    apiClient.post<UsageImportResponse>('/usage/import', payload, { timeout: USAGE_TIMEOUT_MS }),
+
   /**
    * 计算密钥成功/失败统计，必要时会先获取 usage 数据
    */