Switch to local PostgreSQL configuration and improve data handling

Migrates from Neon serverless to local PostgreSQL, fixes timestamp comparisons, and applies Node.js 18 compatibility fixes.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 91318273-c764-4fd4-be04-bdc12c38af32
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/0715008c-7244-40f4-befc-26c014852236/142044c4-d937-4abb-ae50-83d9764cfb4d.jpg

server/data-purge.ts

@@ -18,7 +18,7 @@ export async function purgeSalesData() {
     // Supprimer les ventes antérieures à la date limite
     const result = await db
       .delete(sales)
-      .where(lt(sales.timestamp, cutoffDate.toISOString()))
+      .where(lt(sales.timestamp, cutoffDate))
       .returning({ id: sales.id });
     
     const deletedCount = result.length;
@@ -58,7 +58,7 @@ export async function getPurgeStats() {
     const oldSales = await db
       .select({ id: sales.id })
       .from(sales)
-      .where(lt(sales.timestamp, cutoffDate.toISOString()));
+      .where(lt(sales.timestamp, cutoffDate));
     
     // Compter le total des ventes
     const totalSales = await db