bump mcp sdk (#78)

Author: huozhi

package.json

@@ -32,7 +32,7 @@
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {
-    "@modelcontextprotocol/sdk": "1.20.0",
+    "@modelcontextprotocol/sdk": "1.21.0",
     "find-process": "2.0.0",
     "pid-port": "2.0.0",
     "xmcp": "0.4.0",