new engine: add whisper-medusa support

[mudler]

Is your feature request related to a problem? Please describe.
This card is a tracker to add support to https://github.com/aiola-lab/whisper-medusa

[mudler]

[localai-org-maint-bot]

I’m picking this up. I’ll add Whisper-Medusa as a focused transcription backend following the current backend registration/build conventions, include user-facing configuration docs and focused tests, and open a PR linked to this issue.