uv add disregards venv called venv

[paveldikov]

I think the insistence on .venv (with leading dot) is a bit too much. I get that the idea is to install in the project venv and not any old venv, but there should be a bit of give here.

Perhaps the heuristic should be:

• 'is $VIRTUAL_ENV a subdirectory of dirname pyproject.toml

rather than the current

• 'is $VIRTUAL_ENV equal to $(dirname pyproject.toml)/.venv

Also, note that .venv vs venv is a somewhat controversial choice, with a bunch of people/systems feeling strongly either way. (FWIW, personally I don't, but I'd rather not have to exhort people to rename their venvs.)