fix: eslint & tsserver lsp root detection

[evanreichard]

What does this PR do?

Fixes #7690 - fixes eslint / tsserver LSP root detection when in e.g. monorepo and starting opencode in the git root.

How did you verify your code works?

Ran it locally and tried the repoduction in https://github.com/anomalyco/opencode/issues/7690