Update post scheduling to synchronize with the posts table

Synchronize scheduled post's `scheduledFor` field with the database when updating post schedule in server/routes.ts.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
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server/routes.ts

@@ -840,6 +840,8 @@ export async function registerRoutes(app: Express): Promise<Server> {
       
       if (scheduledAt) {
         updateData.scheduledAt = new Date(scheduledAt);
+        // Synchroniser avec la table posts
+        await storage.updatePost(scheduledPost.postId, { scheduledFor: new Date(scheduledAt) });
       }
       
       if (pageId) {