Add unit tests for mcp-client.ts

[ryoppippi]

Summary

The src/mcp-client.ts module currently lacks dedicated unit tests. While it is indirectly tested through integration tests in src/toolsets/tests/stackone.mcp-fetch.spec.ts, having unit tests would improve test coverage and make it easier to catch regressions.

Current State

• mcp-client.ts is a thin wrapper around MCP SDK's Client and StreamableHTTPClientTransport
• The createMCPClient function creates and returns these instances along with an asyncDispose method
• No dedicated unit tests exist for this module

Suggested Tests

• Verify Client and Transport are correctly initialised with provided options
• Test that asyncDispose properly calls close() on both client and transport
• Test header passing to transport
• Test error handling for invalid URLs

Related Files

• src/mcp-client.ts
• src/toolsets/tests/stackone.mcp-fetch.spec.ts (integration tests)