refactor backend and persist stock campaign queue

src/dataService.ts

@@ -1,4 +1,4 @@
-import type { OrderData } from './types';
+import type { OrderData, StockData } from './types';
 
 const API_URL = import.meta.env.VITE_API_URL || '/api';
 
@@ -33,7 +33,7 @@ export const isAuthenticated = (): boolean => {
   return !!localStorage.getItem('auth_token');
 };
 
-export const fetchStock = async (): Promise<any[]> => {
+export const fetchStock = async (): Promise<StockData[]> => {
     try {
         const token = localStorage.getItem('auth_token');
         const response = await fetch(`${API_URL}/stock`, {
@@ -47,7 +47,7 @@ export const fetchStock = async (): Promise<any[]> => {
         }
         if (!response.ok) return [];
         return await response.json();
-    } catch (error) {
+    } catch {
         return [];
     }
 };
@@ -89,7 +89,7 @@ export const parseOrderDate = (dateStr: string): Date => {
   return isNaN(fallback.getTime()) ? new Date(0) : fallback;
 };
 
-export const exportToCSV = (data: any[], filename: string) => {
+export const exportToCSV = (data: Record<string, unknown>[], filename: string) => {
   if (!data || !data.length) return;
   
   const headers = Object.keys(data[0]);
@@ -102,7 +102,7 @@ export const exportToCSV = (data: any[], filename: string) => {
   for (const row of data) {
     const values = headers.map(header => {
       const val = row[header];
-      const escaped = ('' + val).replace(/"/g, '\\"');
+      const escaped = String(val ?? '').replace(/"/g, '""');
       return `"${escaped}"`;
     });
     csvRows.push(values.join(','));