Add clean .env.example template file

- Secure template with placeholder values
- No sensitive tokens included

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.env.example

@@ -0,0 +1,16 @@
+# HuggingFace Token (선택사항)
+# HUGGINGFACE_TOKEN=your_huggingface_token_here
+
+# OpenAI API Key (필수)
+# OPENAI_API_KEY=your_openai_api_key_here
+
+# Supabase 설정 (필수)
+# SUPABASE_URL=https://your-project.supabase.co
+# SUPABASE_KEY=your_supabase_key_here
+
+# 벡터 DB 타입 (faiss 또는 supabase)
+VECTOR_DB_TYPE=supabase
+
+# 기존 FAISS 설정 (VECTOR_DB_TYPE=faiss 인 경우 사용)
+EMBEDDING_MODEL=jhgan/ko-sbert-nli
+LLM_MODEL=beomi/Llama-3-Open-Ko-8B