Enable users to upload videos to the platform on all devices

Reset the file input value after a file upload or rejection to prevent issues with subsequent uploads on Android.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Event-Id: 514638b9-84d2-4a7a-8ec1-ae6513635dd7
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/397bca8c-984f-43ff-841a-10897aeb8140/ae4037a0-2a6f-4530-9bac-79b543286bda/ofL5rPP

client/src/pages/new-post.tsx

@@ -324,10 +324,12 @@ export default function NewPost() {
           variant: "destructive",
         });
         console.error('❌ Fichier rejeté: trop volumineux');
+        e.target.value = '';
         return;
       }
 
       uploadMutation.mutate(fileToUpload);
+      e.target.value = '';
     }
   };