add conda-managed-env

[jjhelmus]

When the conda-managed-env package is installed into an environment, pip and other tools are blocked from installing packages as documented in Externally Managed Environments

For example:

❯ conda list conda-
# packages in environment at /Users/jhelmus/mc/envs/test:
#
# Name                    Version                   Build  Channel
conda-managed-env         1.0.0                   py310_0    local

❯ python -m pip install imagesize
error: externally-managed-environment

× This environment is externally managed
╰─> This conda environment has been marked as externally managed.
    Please use conda to install packages into this environment.

    If you wish to install packages using other tools, consider creating
    a new environment or remove the conda-managed-env package from
    this environment.

note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.

Checklist

• Title of this PR is meaningful: e.g. "Adding my_nifty_package", not "updated meta.yaml".
• License file is packaged (see here for an example).
• Source is from official source.
• Package does not vendor other packages. (If a package uses the source of another package, they should be separate packages or the licenses of all packages need to be packaged).
• If static libraries are linked in, the license of the static library is packaged.
• Package does not ship static libraries. If static libraries are needed, follow CFEP-18.
• Build number is 0.
• A tarball (url) rather than a repo (e.g. git_url) is used in your recipe (see here for more details).
• GitHub users listed in the maintainer section have posted a comment confirming they are willing to be listed there.
• When in trouble, please check our knowledge base documentation before pinging a team.

[github-actions]

Hi! This is the staged-recipes linter and I found some lint.

File-specific lints and/or hints:

• recipes/conda-managed-env/meta.yaml:
  • lints:
    • Feedstock with the same name exists in conda-forge.

[jjhelmus]

Note that this cannot be a noarch: python package as the EXTERNALLY-MANAGED file needs to be placed in the standard library directory (lib/python3.x) not the site-packages directory (lib/python3.x/site-packages)

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I wanted to let you know that I linted all conda-recipes in your PR (recipes/conda-managed-env/meta.yaml) and found some lint.

Here's what I've got...

For recipes/conda-managed-env/meta.yaml:

• ❌ The recipe must have a build/number section.
• ❌ The about section contained an unexpected subsection name. descriptions is not a valid subsection name.

_{This message was generated by GitHub Actions workflow run https://github.com/conda-forge/conda-forge-webservices/actions/runs/13708796731. Examine the logs at this URL for more detail.}

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipes/conda-managed-env/meta.yaml) and found it was in an excellent condition.

[jjhelmus]

A feedstock and packages already exists due to accidental direct push to main (c8fe328)