Kyoo: Transcoder serves uncataloged files from the media directory

Kyoo is a self-hosted media server focused on movies, series, and anime. Prior to 5.1.0, a registered user with the core.play permission could supply a base64-encoded filesystem path to the transcoder. The path handling in transcoder/src/api/path.go cleaned the value and checked only that it began with Settings.SafePath before getHash processed it, while transcoder/src/api/streams.go served the accepted path without verifying a Kyoo catalog record. This missing catalog-level authorization allowed the user to retrieve hidden, temporary, operational, or other uncataloged files beneath the media directory when the path was known or guessed. This vulnerability is fixed in 5.1.0.