Make mcp server awaitable

[sparfenyuk]

This change fixes the problem of connecting to the server through mcp-proxy:

mcp-proxy --sse-port=9991 --pass-environment -- bunx mcp-server-code-runner@latest

[formulahendry]

Hi @sparfenyuk , thanks for you PR, and mcp-proxy looks awesome!
As server.connect(transport) is just return a void, I'd like to learn more why we need to return it to make mcp-proxy work?
If we really need to do that, then we need to put console.debug("Code Runner MCP Server running on stdio"); after main()?

[sparfenyuk]

An instance of Promise is returned, and it's important for the promise chain. This is why main().catch((error) => {}) is written.

[sparfenyuk]

If we really need to do that, then we need to put console.debug("Code Runner MCP Server running on stdio"); after main()?

In such scenario, the log wouldn't be displayed unless the script is stopped, I believe. So, keep it as it is.