Fix multipart upload progress display by adding ProcessQueuedUpdates calls

� PROGRESS DISPLAY FIX:

✅ MISSING PROGRESS PROCESSING:
  • Added ProcessQueuedUpdates() calls throughout multipart upload
  • Progress was being queued but never displayed to user
  • Now processes progress updates immediately after key events

� PROGRESS PROCESSING POINTS:
  • After initial progress setup (Layer 1 & 2 initialization)
  • After upload ID logging and configuration display
  • After each part completion with updated file progress
  • After final completion of all progress layers

� EXPECTED RESULTS:
  • 3-layer progress bars now visible during upload
  • Collection progress shows overall operation
  • File progress shows parts completed with speed
  • Chunk progress shows individual part upload (when implemented)
  • Real-time progress updates during long operations

� TECHNICAL DETAILS:
  • ThreadSafeProgressCollector queues updates from background threads
  • ProcessQueuedUpdates() must be called from main thread to display
  • Added strategic calls at key progress milestones
  • Maintains thread safety while ensuring visibility

Now multipart uploads show proper 3-layer progress tracking!

src/Core/S3/MultipartUploadManager.cs

@@ -62,6 +62,9 @@ namespace PSMinIO.Core.S3
             _progressCollector.QueueProgressUpdate(2, "File Upload",
                 $"Uploading {fileInfo.Name} ({SizeFormatter.FormatBytes(totalSize)})", 0, 1);
 
+            // Process initial progress updates
+            _progressCollector.ProcessQueuedUpdates();
+
             var uploadId = resumeUploadId;
             var parts = new ConcurrentDictionary<int, PartInfo>();
             var operationStartTime = DateTime.UtcNow;
@@ -94,6 +97,9 @@ namespace PSMinIO.Core.S3
                 _progressCollector.QueueVerboseMessage("Upload configuration - Chunk size: {0}, Total parts: {1}, Max parallel: {2}",
                     SizeFormatter.FormatBytes(effectiveChunkSize), totalParts, _maxParallelUploads);
 
+                // Process verbose messages and progress updates
+                _progressCollector.ProcessQueuedUpdates();
+
                 // Upload parts in parallel
                 var uploadTasks = new List<Task>();
                 var semaphore = new SemaphoreSlim(_maxParallelUploads, _maxParallelUploads);
@@ -134,6 +140,9 @@ namespace PSMinIO.Core.S3
 
                             _progressCollector.QueueVerboseMessage("Completed part {0}/{1} ({2})",
                                 partNum, totalParts, SizeFormatter.FormatBytes(partSize));
+
+                            // Process progress updates immediately
+                            _progressCollector.ProcessQueuedUpdates();
                         }
                         finally
                         {
@@ -162,6 +171,9 @@ namespace PSMinIO.Core.S3
                 _progressCollector.QueueProgressCompletion(2, "File Upload", 1);
                 _progressCollector.QueueProgressCompletion(1, "Multipart Upload Collection");
 
+                // Process final progress updates
+                _progressCollector.ProcessQueuedUpdates();
+
                 return new MultipartUploadResult
                 {
                     BucketName = bucketName,