Improve: Add comprehensive error handling and logging

Enhanced the fix based on code review feedback:
1. Added error handling at ProcessPageAsync level to ensure one failing item
   doesn't block processing of other items in the batch
2. Added explicit exception logging in ProcessItemAsync to surface errors
   during workflow resumption
3. Changed deletion to use CancellationToken.None to ensure cleanup happens
   even during application shutdown
4. Added detailed comments explaining error handling strategy

These improvements ensure the system is robust and provides visibility into
any issues while still guaranteeing queue items are cleaned up properly.

Co-authored-by: sfmskywalker <938393+sfmskywalker@users.noreply.github.com>

Author: Copilot

src/modules/Elsa.Workflows.Runtime/Services/BookmarkQueueProcessor.cs

@@ -30,8 +30,18 @@ public async Task ProcessAsync(CancellationToken cancellationToken = default)
 
     private async Task ProcessPageAsync(Page<BookmarkQueueItem> page, CancellationToken cancellationToken = default)
     {
-        foreach (var bookmarkQueueItem in page.Items) 
-            await ProcessItemAsync(bookmarkQueueItem, cancellationToken);
+        foreach (var bookmarkQueueItem in page.Items)
+        {
+            try
+            {
+                await ProcessItemAsync(bookmarkQueueItem, cancellationToken);
+            }
+            catch (Exception ex)
+            {
+                // Log the error but continue processing other items in the batch
+                logger.LogError(ex, "Error processing bookmark queue item {BookmarkQueueItemId}. Continuing with next item.", bookmarkQueueItem.Id);
+            }
+        }
     }
 
     private async Task ProcessItemAsync(BookmarkQueueItem item, CancellationToken cancellationToken = default)
@@ -54,14 +64,19 @@ private async Task ProcessItemAsync(BookmarkQueueItem item, CancellationToken ca
                 logger.LogDebug("No matching bookmarks found for bookmark queue item {BookmarkQueueItemId} for workflow instance {WorkflowInstanceId} for activity type {ActivityType} with stimulus {StimulusHash}. The bookmark may have already been processed by another queue item.", item.Id, item.WorkflowInstanceId, item.ActivityTypeName, item.StimulusHash);
             }
         }
+        catch (Exception ex)
+        {
+            logger.LogError(ex, "Error resuming workflow for bookmark queue item {BookmarkQueueItemId} for workflow instance {WorkflowInstanceId}. The queue item will still be deleted to prevent accumulation.", item.Id, item.WorkflowInstanceId);
+        }
         finally
         {
             // Always delete the queue item after processing, regardless of whether bookmarks were found or an exception occurred.
             // This prevents duplicate queue items from accumulating when the same bookmark is queued multiple times in rapid succession.
             // The distributed lock in WorkflowResumer ensures that the actual bookmark is only processed once.
+            // Use CancellationToken.None to ensure cleanup happens even during application shutdown.
             try
             {
-                await store.DeleteAsync(item.Id, cancellationToken);
+                await store.DeleteAsync(item.Id, CancellationToken.None);
             }
             catch (Exception ex)
             {