Enable scheduling and posting to Facebook and Instagram pages

Fix bug in post creation to correctly handle media, page selection, and scheduling for social media posts.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/397bca8c-984f-43ff-841a-10897aeb8140/ae4037a0-2a6f-4530-9bac-79b543286bda/sjuGm8z

client/src/pages/new-post.tsx

@@ -106,9 +106,21 @@ export default function NewPost() {
       return;
     }
 
+    if (selectedPages.length === 0) {
+      toast({
+        title: "Page requise",
+        description: "Veuillez sélectionner au moins une page",
+        variant: "destructive",
+      });
+      return;
+    }
+
     createPostMutation.mutate({
       content: postText,
       scheduledFor: scheduledDate || undefined,
+      mediaId: selectedMedia || undefined,
+      pageIds: selectedPages,
+      postType: 'feed', // Default to feed post
     });
   };