feat(knowledge): resolve remote images in file upload path

The file upload pipeline (ProcessDocument) only called ResolveAndStore(),
which handles inline bytes and base64 data URIs but explicitly skips
http/https URLs. This meant markdown files with external image URLs
(e.g. GitHub issue screenshots) were never downloaded, stored, or
processed by VLM multimodal.

Add ResolveRemoteImages() call after ResolveAndStore() in the file
upload path, matching the existing manual processing path behavior.

internal/application/service/knowledge.go

@@ -7576,7 +7576,20 @@ func (s *knowledgeService) ProcessDocument(ctx context.Context, t *asynq.Task) e
 			convertResult.MarkdownContent = updatedMarkdown
 		}
 		storedImages = images
-		logger.Infof(ctx, "Resolved %d images for knowledge %s", len(storedImages), knowledge.ID)
+
+		// Resolve remote http(s) images (e.g. markdown external URLs) → download + upload to storage.
+		// ResolveAndStore handles inline bytes and base64; ResolveRemoteImages handles http/https URLs.
+		updatedContent, remoteImages, remoteErr := s.imageResolver.ResolveRemoteImages(ctx, convertResult.MarkdownContent, fileSvc, tenantID)
+		if remoteErr != nil {
+			logger.Warnf(ctx, "Remote image resolution partially failed: %v", remoteErr)
+		}
+		if len(remoteImages) > 0 {
+			logger.Infof(ctx, "Resolved %d remote images for knowledge %s", len(remoteImages), knowledge.ID)
+			convertResult.MarkdownContent = updatedContent
+			storedImages = append(storedImages, remoteImages...)
+		}
+
+		logger.Infof(ctx, "Resolved %d total images for knowledge %s", len(storedImages), knowledge.ID)
 	}
 
 	// Step 3: Split into chunks using Go chunker