docs(config): add siliconflow demo env template

.env.siliconflow.example

@@ -0,0 +1,21 @@
+DJANGO_SECRET_KEY=replace-with-a-local-secret-key
+DJANGO_DEBUG=true
+DJANGO_ALLOWED_HOSTS=*
+
+# SiliconFlow OpenAI-compatible API
+# Fill these two keys manually before demo.
+LLM_PROVIDER=openai_compatible
+LLM_API_KEY=your_siliconflow_api_key
+LLM_BASE_URL=https://api.siliconflow.cn/v1
+LLM_MODEL=Qwen/Qwen2.5-7B-Instruct
+
+# SiliconFlow embedding model for RAG.
+# You can reuse the same SiliconFlow key here.
+EMBEDDING_API_KEY=your_siliconflow_api_key
+EMBEDDING_BASE_URL=https://api.siliconflow.cn/v1
+EMBEDDING_MODEL=BAAI/bge-m3
+
+SCENARIO_CONFIG_DIR=configs
+GOVERNANCE_CONFIG_PATH=configs/governance.yaml
+UPLOAD_ROOT=data/uploads
+CHROMA_PATH=data/chroma