Issue : Missing API Token Check

[PrinceSajjadHussain]

The code retrieves the REPLICATE_API_TOKEN from the environment, but it doesn't check if it's actually set. If the token is not set, the replicate library will likely throw an error later on, but this error will be less clear about the actual problem. Adding a check and returning a useful error message if it's missing will improve the user experience and ease debugging.