Backend returns extensions with a leading dot (e.g., `.png` from `os.path.splitext`), causing binary/media files to be misclassified as text since they didn't match the dot-free extension lists.
Backend returns extensions with a leading dot (e.g., `.png` from `os.path.splitext`), causing binary/media files to be misclassified as text since they didn't match the dot-free extension lists.