Fix RFM date range consistency

src/dataService.ts

@@ -1,4 +1,5 @@
 import type { CampaignPreview, CampaignProcessSummary, CampaignQueueSummary, DashboardAnalytics, DateRange, OrderData, RfmAnalytics, StockData } from './types';
+import { formatDateParam } from './dateRanges';
 
 const API_URL = import.meta.env.VITE_API_URL || '/api';
 
@@ -89,13 +90,6 @@ const authFetch = async (path: string, options: RequestInit = {}): Promise<Respo
     return response;
 };
 
-const formatDateParam = (date: Date): string => {
-    const year = date.getFullYear();
-    const month = String(date.getMonth() + 1).padStart(2, '0');
-    const day = String(date.getDate()).padStart(2, '0');
-    return `${year}-${month}-${day}`;
-};
-
 export const fetchDashboardAnalytics = async (dateRange: DateRange): Promise<DashboardAnalytics | null> => {
     try {
         const params = new URLSearchParams({