fix(kokoros): implement AudioTranscriptionLive trait stub (#10612)

The backend.proto AudioTranscriptionLive bidirectional streaming RPC added
new required trait items (AudioTranscriptionLiveStream + audio_transcription_live)
on the generated Backend trait. The kokoros (TTS) backend did not implement
them, breaking its release build with E0046 (missing trait items).

kokoros is text-to-speech and has no live-ASR support, so stub the method to
return UNIMPLEMENTED, mirroring the existing audio_transcription_stream stub.


Assisted-by: Claude:claude-opus-4-8 [Claude Code]

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>

backend/rust/kokoros/src/service.rs

@@ -351,6 +351,16 @@ impl Backend for KokorosService {
         Err(Status::unimplemented("Not supported"))
     }
 
+    type AudioTranscriptionLiveStream =
+        ReceiverStream<Result<backend::TranscriptLiveResponse, Status>>;
+
+    async fn audio_transcription_live(
+        &self,
+        _: Request<tonic::Streaming<backend::TranscriptLiveRequest>>,
+    ) -> Result<Response<Self::AudioTranscriptionLiveStream>, Status> {
+        Err(Status::unimplemented("Not supported"))
+    }
+
     async fn diarize(
         &self,
         _: Request<backend::DiarizeRequest>,