docs: add Brainy Chat preview documentation

- Introduce upcoming chat feature for v0.56
- Zero additional dependencies using existing embeddings
- RAG-based Q&A over your data
- Multiple deployment options (embedding-only, local LLM, API)
- Updated README to highlight chat feature

README.md

@@ -13,6 +13,21 @@
 
 ---
 
+# 🆕 Coming Soon: Talk to Your Data with Brainy Chat! 
+
+**Transform your database into an AI that understands your data:**
+
+```javascript
+// Coming in v0.56!
+const chat = await BrainyChat.create(brainy)
+const answer = await chat.ask("What patterns do you see in customer behavior?")
+// → AI analyzes YOUR data and relationships to provide insights
+```
+
+[📖 **Learn More About Brainy Chat**](BRAINY-CHAT.md) | **Zero extra dependencies** | **Uses existing embeddings**
+
+---
+
 # 🆕 Introducing Cortex - Configuration & Coordination Command Center
 
 **Never manage .env files again!** Cortex brings encrypted configuration management and distributed coordination to Brainy: