Auto Set Image Alt From Filename

How can you auto set image alt from filename in WordPress? This use case shows how a focused WordPress code snippet can handle the task without installing a heavy plugin. The snippet should set image alt text from filename on upload and produce this result: Uploaded images get an alt text generated from the cleaned filename. You can also log in to LeonLab.ai, describe this WordPress use case in plain English, generate the snippet, review the PHP code, and deploy it to the selected WordPress project.