Enable support for multiple products within a single sale

Implements multi-product sales functionality by adding a `sale_products` table, updating the sales form, and modifying server-side logic.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: e80fed01-7137-4997-b9af-dad57132d430
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/0715008c-7244-40f4-befc-26c014852236/e80fed01-7137-4997-b9af-dad57132d430/58t7aEc

client/src/types/sale.ts

@@ -1,3 +1,11 @@
+export interface SaleProduct {
+  id?: number;
+  typeArticle: string;
+  categorie: 'F2' | 'F3';
+  quantite: number;
+  gencode: string;
+}
+
 export interface Sale {
   id: number;
   timestamp: string;
@@ -5,12 +13,6 @@ export interface Sale {
   // Vendeur
   vendeur: string;
   
-  // Produit
-  typeArticle: string;
-  categorie: 'F2' | 'F3';
-  quantite: number;
-  gencode: string;
-  
   // Client
   nom: string;
   prenom: string;
@@ -28,14 +30,19 @@ export interface Sale {
   photo_recto?: string;
   photo_verso?: string;
   photo_ticket?: string;
+  
+  // Produits (nouveaux)
+  products?: SaleProduct[];
 }
 
 export interface FormData {
   vendeur: string;
-  typeArticle: string;
-  categorie: string;
-  quantite: string;
-  gencode: string;
+  products: {
+    typeArticle: string;
+    categorie: string;
+    quantite: string;
+    gencode: string;
+  }[];
   nom: string;
   prenom: string;
   dateNaissance: string;