docs: update version to v0.3

Author: NeurArk

README.md

@@ -5,7 +5,7 @@
 📄 [MCP schema](static/schema.json)
 🔖 [Latest release](https://github.com/NeurArk/mcp-data-assistant/releases/latest)
 
-**Data Assistant MVP v0.2** – a fully-local Model Context Protocol
+**Data Assistant MVP v0.3** – a fully-local Model Context Protocol
 server that lets any modern LLM:
 
 * **run_sql** – safely query a SQLite database