[voice] feat: add managed voice cloning profiles (#10799)

* feat(ui): add voice library workflow

Give administrators a production-ready flow to record or upload consented reference audio, manage reusable profiles, inspect API usage, discover compatible models, and hand a saved voice directly to text-to-speech.

Assisted-by: Codex:gpt-5

* feat(voice): add managed voice cloning profiles

Make reusable reference voices manageable through the admin API instead of requiring model-directory and YAML edits. Discover compatible installed and gallery models from server-side backend capabilities, retain explicit model configuration controls, and stage saved references for supported backends.

Expose profile management through REST and MCP, document backend-specific behavior, and cover the workflow from profile creation through real Qwen3-TTS synthesis. Harden the agent-job HTTP test against completion racing cancellation.

Assisted-by: Codex:gpt-5

---------

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

backend/python/chatterbox/backend.py

@@ -199,7 +199,9 @@ class BackendServicer(backend_pb2_grpc.BackendServicer):
 
             if "language" in self.options:
                 kwargs["language_id"] = self.options["language"]
-            if self.AudioPath is not None:
+            if request.voice and os.path.isfile(request.voice):
+                kwargs["audio_prompt_path"] = request.voice
+            elif self.AudioPath is not None:
                 kwargs["audio_prompt_path"] = self.AudioPath
 
             # add options to kwargs
@@ -211,6 +213,8 @@ class BackendServicer(backend_pb2_grpc.BackendServicer):
             # strings on the wire and are coerced to float/int/bool.
             if hasattr(request, "params") and request.params:
                 for key, value in request.params.items():
+                    if key == "ref_text":
+                        continue
                     kwargs[key] = coerce_param_value(value)
 
             # Check if text exceeds 250 characters