Fix samples/kotlin-mcp-server

**Describe the bug**
The multiplatform project got broken. It doesn't compile.

**To Reproduce**
Steps to reproduce the behavior:
`(cd samples/kotlin-mcp-server && ./gradlew clean build`

**Expected behavior**
Project compiles, tests are green. Server is runnable and works with [MCP Inspector]

**Additional context**
See #330 
