Remove manual date entry and automate timestamp for new sales records

Removes dateVente field from NewSaleForm, sale types, and shared schema.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: dec54137-d5a2-4406-8ad4-5f2f9fb110bf
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/0715008c-7244-40f4-befc-26c014852236/fa7f08e0-2cf1-49d3-8250-af23db9cc3bd.jpg

shared/schema.ts

@@ -60,7 +60,6 @@ export const sales = pgTable("sales", {
   
   // Vendeur
   vendeur: varchar("vendeur", { length: 255 }).notNull(),
-  dateVente: varchar("date_vente", { length: 10 }).notNull(),
   
   // Produit
   typeArticle: varchar("type_article", { length: 255 }).notNull(),