Fix error when directly changing into subdirectory of a devenv folder

[domu1de]

dev 1.8.1
zsh 5.9 (x86_64-apple-darwin22.0)

When changing directly into a subdirectory of a devenv folder from outside (e.g., cd project/subdir), the following error occurs:

no devenv detected
(eval):1: permission denied: /Users/.../project

This happens because the devenv root directory wasn’t correctly passed to the dev command, which is required for proper initialization in such cases.

This PR fixes the issue by ensuring the correct devenv folder is passed, even when entering subdirectories directly.

[gaggle]

I don't mean to disturb maintainers, but wondering if I may do a gentle nudge to hear if bandwidth is available for landing this? It'd be a nice fix! I'll gently cc @mxcl / @jhheider