fix: correct FastMCP API usage for root path

esm/mcp_output/mcp_plugin/mcp_service.py

@@ -261,7 +261,7 @@ def create_app():
         FastMCP: MCP service instance.
     """
     # Add root path handler for health check
-    @mcp.app.get("/")
+    @mcp.get("/")
     async def root():
         return {"status": "ok", "service": "Code2MCP-esm", "transport": "http"}