feat: Add voice assistant handler and Kubeflow pipeline

- voice_assistant.py: Standalone NATS handler with full RAG pipeline
- voice_assistant_v2.py: Handler-base implementation
- pipelines/voice_pipeline.py: KFP SDK pipeline definitions
- Dockerfiles for both standalone and handler-base versions

Pipeline: STT → Embeddings → Milvus → Rerank → LLM → TTS

requirements.txt

@@ -0,0 +1,15 @@
+nats-py
+httpx
+pymilvus
+numpy
+msgpack
+redis>=5.0.0
+opentelemetry-api
+opentelemetry-sdk
+opentelemetry-exporter-otlp-proto-grpc
+opentelemetry-exporter-otlp-proto-http
+opentelemetry-instrumentation-httpx
+opentelemetry-instrumentation-logging
+# MLflow for inference metrics tracking
+mlflow>=2.10.0
+psycopg2-binary>=2.9.0