pixi feat: Relative path support in LockFile

Description

Make pixi handle relative paths to pypi dependencies in the LockFile. This helps when checking in pixi.lock files that reference local python packages. Instead of ending up with a machine specific path in the lock file we have a relative path that should work for all developers.

This depends on the rattler part which is here: https://github.com/conda/rattler/pull/1760

The PR consists of several changes:

Update to the rattler_lock API changes made in conda/rattler#1760
Make sure the non-pep508-extensions are enabled in pixi as well
Convert between uv relative paths and pixi relative paths

Note: This only works with pixi.log, not when storing the pixi configuration inline in pyproject.toml. Pyproject.toml will need to get an update to enable it to handle relative paths (like accept a work directory when parsing the file as well as non-pep508-extension support). I did not want to complicate this PR by requiring another PR to yet another crate.

Relates to: #4680

Oct 19 '25 12:10 hunger

CI fails right now since rattler_lock does not have the required version.

Oct 19 '25 15:10 hunger

Updated the change about adapting to rattler API changes.

Oct 20 '25 16:10 hunger

Maybe we can patch the rattler versions in this PR? So we can see if CI runs and then change it back after a rattler release?

Oct 22 '25 08:10 tdejager