support mod_cartesia_transcribe (#1245)

lib/session/call-session.js

@@ -1097,6 +1097,7 @@ class CallSession extends Emitter {
           return {
             api_key: credential.api_key,
             model_id: credential.model_id,
+            stt_model_id: credential.stt_model_id,
             embedding: credential.embedding,
             options: credential.options
           };