Compare tunnel key identity when a healthy worker is unreachable

When a proxy cannot reach a healthy inference worker through an SSH tunnel, compare the tunnel credential's derived public-key fingerprint with the worker's authorized keys before changing model or proxy configuration. A running tunnel container and a healthy worker can coexist with failed authentication; the public synthesis request is the decisive check. Restore the already configured tunnel identity only on the intended worker, then retry a complete audio request. This identifies an authentication break, but does not by itself explain when or why the key was removed.

Applies when: A separately hosted worker is reached through an SSH tunnel and public synthesis fails before audio. Keywords: SSH tunnel public key fingerprint authorized_keys proxy upstream authentication synthesis GPU