feat: Add start of uv vs. Pixi

[matthewfeickert]

@henryiii direction on what sort of story you would like here would be useful for finishing this today.

[matthewfeickert]

I am going to empirically verify this in the morning. If this needs to get merged before this should be deleted.

[matthewfeickert]

Seems good:

$ pixi init no-install-lock && cd no-install-lock && pixi add --no-install python && pixi add --no-install --pypi scipy && ls -lhtra .pixi/ && pixi lock
✔ Created /tmp/no-install-lock/pixi.toml
✔ Added python >=3.14.6,<3.15
✔ Added scipy >=1.18.0, <2
Added these as pypi-dependencies.
total 16K
-rw-rw-r-- 1 feickert feickert   15 Jul 13 00:33 .gitignore
-rw-rw-r-- 1 feickert feickert   25 Jul 13 00:33 .condapackageignore
drwxrwxr-x 2 feickert feickert 4.0K Jul 13 00:33 .
drwxrwxr-x 3 feickert feickert 4.0K Jul 13 00:33 ..
✔ Lock-file was already up-to-date

[workspace]
channels = ["conda-forge"]
name = "no-install-lock"
platforms = ["linux-64"]
version = "0.1.0"

[tasks]

[dependencies]
python = ">=3.14.6,<3.15"

[pypi-dependencies]
scipy = ">=1.18.0, <2"

[matthewfeickert]

Maybe that's not a full example though of what you had in mind.

[matthewfeickert]

Ah no, you meant for development (duh) and then it is still a problem

$ git clone git@github.com:scikit-hep/boost-histogram.git && cd boost-histogram && pixi init --format pyproject && pixi lock --no-install
Cloning into 'boost-histogram'...
remote: Enumerating objects: 9574, done.
remote: Counting objects: 100% (81/81), done.
remote: Compressing objects: 100% (74/74), done.
remote: Total 9574 (delta 33), reused 11 (delta 5), pack-reused 9493 (from 1)
Receiving objects: 100% (9574/9574), 3.56 MiB | 3.54 MiB/s, done.
Resolving deltas: 100% (7023/7023), done.
✔ Added package 'boost-histogram' as an editable dependency.
✔ Added environments 'github', 'test', 'dev', 'docs', 'examples' from optional dependencies or dependency groups.
▪ solving              [━━━━━━━━━━━━━━━━━━━━]  1/1                                                                                                                  ⠒ updating lock file   [00:00:00] [────────────────────────────────────────]    0/8                                                                                 
thread 'main2' (1830632) panicked at crates/pixi_core/src/lock_file/resolve/build_dispatch.rs:477:17:
could not initialize build dispatch correctly
Error:   × failed to solve the pypi requirements of environment 'default' for platform 'linux-64'
  ╰─▶ build dispatch initialization failed: installation of conda environment is required to solve PyPI source dependencies but `--no-install` flag has been set

[matthewfeickert]

@henryiii if you approve of this as is then one of us can generate the slides and this can go in.