feat: add get schema tool

backend/test_nl2sql.py

@@ -0,0 +1,12 @@
+import asyncio
+import json
+from app.agent.nl2sql import process_nl2sql, NL2SQLRequest
+
+async def main():
+    req = NL2SQLRequest(query="列出所有表", source="postgres", generate_chart=False)
+    res = await process_nl2sql(req)
+    print("SQL:", res.sql)
+    print("Error:", res.error)
+    print("Result:", res.result)
+
+asyncio.run(main())