feat: add remote vLLM support with provider abstraction layer

- LLMClient Protocol for provider-agnostic inference
- VLLMClient for OpenAI-compatible /v1/chat/completions API
- LLM client factory with provider routing (ollama/vllm)
- VLLMConfig with VLLM_* environment variable loading
- Updated extractor worker with health check and provider switching
- Updated event classifier to use LLMClient protocol
- Helm values for vLLM configuration
- 18 unit tests + 6 property-based tests
- Full backward compatibility preserved

infra/helm/stonks-oracle/values.yaml

@@ -181,6 +181,12 @@ config:
   OLLAMA_RETRY_BASE_DELAY: "1.0"
   OLLAMA_RETRY_MAX_DELAY: "10.0"
   OLLAMA_RETRY_BACKOFF_MULTIPLIER: "2.0"
+  VLLM_BASE_URL: "http://192.168.42.254:8000"
+  VLLM_MODEL: "RedHatAI/Qwen3.6-35B-A3B-NVFP4"
+  VLLM_TIMEOUT: "120"
+  VLLM_MAX_RETRIES: "2"
+  VLLM_TEMPERATURE: "0.7"
+  VLLM_API_KEY: ""
   TRINO_HOST: "trino.stonks-oracle.svc.cluster.local"
   TRINO_PORT: "8080"
   TRINO_CATALOG: "lakehouse"