Add preview URL logging and clean up MinIO verbose logs

- Add logging for generated preview URLs with truncated URL for security
- Remove verbose logging from MinIO listObjectsV2 operations
- Add proper handling for folder prefixes returned by MinIO
- Keep only essential error/debug information in file listing

server/api/files/preview.ts

@@ -37,6 +37,12 @@ export default defineEventHandler(async (event) => {
     // Generate presigned URL for preview
     const url = await getPreviewUrl(fileName, contentType);
     
+    console.log('Preview URL generated:', {
+      fileName,
+      contentType,
+      url: url.substring(0, 100) + '...' // Log first 100 chars for security
+    });
+    
     return {
       success: true,
       url,