fix(deps): update @modelcontextprotocol/sdk requirement in /packages/mcp

Updates the requirements on [@modelcontextprotocol/sdk](https://github.com/modelcontextprotocol/typescript-sdk) to permit the latest version.
- [Release notes](https://github.com/modelcontextprotocol/typescript-sdk/releases)
- [Commits](modelcontextprotocol/typescript-sdk@1.16.0...1.18.0)

---
updated-dependencies:
- dependency-name: "@modelcontextprotocol/sdk"
  dependency-version: 1.18.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

packages/mcp/package.json

@@ -42,7 +42,7 @@
     "package.json"
   ],
   "dependencies": {
-    "@modelcontextprotocol/sdk": "^1.16.0",
+    "@modelcontextprotocol/sdk": "^1.18.0",
     "@oclif/core": "^4.5.1",
     "@salesforce/agents": "^0.15.4",
     "@salesforce/apex-node": "^8.2.1",