fix: broadcast S3DownloadFinished event to hide download message

- Make S3DownloadFinished implement ShouldBroadcast
- Add listener in Import component to handle S3DownloadFinished event
- Set s3DownloadInProgress to false when download completes
- This hides "Downloading from S3..." message after download finishes
- Follows the same pattern as DatabaseStatusChanged event

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/Livewire/Project/Database/Import.php

@@ -74,9 +74,15 @@ class Import extends Component
 
         return [
             "echo-private:user.{$userId},DatabaseStatusChanged" => '$refresh',
+            "echo-private:user.{$userId},S3DownloadFinished" => 'handleS3DownloadFinished',
         ];
     }
 
+    public function handleS3DownloadFinished(): void
+    {
+        $this->s3DownloadInProgress = false;
+    }
+
     public function mount()
     {
         if (isDev()) {