feat(client): add LM Studio support

[reegnz]

The change allows the LM Studio mcp config found under ~/.lmstudio/mcp.json
to be discovered and updated with the toolhive-managed mcp servers.

Fixes #1529

[eleftherias]

Thanks @reegnz!
Just a couple of comments before we merge this.

1. Could you run task docs to ensure the documentation gets updated with the new client
2. We have 2 tests that check the format for each client, the first one is here https://github.com/stacklok/toolhive/blob/main/pkg/client/config_test.go#L275 and the second one is here https://github.com/stacklok/toolhive/blob/main/pkg/client/config_test.go#L329

[eleftherias]

Thanks @reegnz! I included a small commit to fix the linting.

[reegnz]

@eleftherias thanks! Sorry but I couldn't get around to adding the tests this week.