Run the developer mcp in a login shell

[jamadeo]

I'm not sure we want to do this, but if we do, this would probably be the way

[michaelneale]

I think this may be worthwhile, previously, it would inherit it from the forced loading on macos, but now people may find it is missing things they expect are on their $PATH, so this would be closer to what you run if you run from cli, so principle of least surprise: I think yes?

What is downside to this?

[wpfleger96]

I just opened #5680 before I realized this draft PR was already open for this, FWIW I am definitely in favor of running a login shell bc I've found the developer extension in goose UI/desktop to be pretty limited now - it can no longer run any non system PATH command which includes rg, node/npm, pip/uv, jq, yq, etc. Not having rg in particular is tough since goose makes heavy use of it during local development and when exploring local codebases

This also breaks Presidio MCP for Block users in UI/desktop, because that MCP implementation uses subprocess.run() to launch sq presidio which similarly fails since sq is also installed via Homebrew

[jamadeo]

done in #5774