gh-1159: Add CosmologyWithOmegaM protocol

[paddyroddy]

Description

Adds a CosmologyWithOmegaM protocol as OmegaM isn't used that often.

Closes: #1159

Changelog entry

Added: A CosmologyWithOmegaM protocol

Checks

• Is your code passing linting?
• Is your code passing tests?
• Have you added additional tests (if required)?
• Have you modified/extended the documentation (if required)?
• Have you added a one-liner changelog entry above (if required)?

[Copilot]

Pull request overview

Adds a more specific typing protocol (CosmologyWithOmegaM) to represent cosmology objects that provide Omega_m(z), and uses it where Omega_m is actually required (e.g., density-based shell weights). This refines type contracts in GLASS without changing runtime behavior.

Changes:

• Introduce CosmologyWithOmegaM protocol in glass.cosmology.
• Update DensityWeight to require CosmologyWithOmegaM instead of the broader Cosmology.
• Adjust the corresponding unit test type annotation for DensityWeight.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
glass/cosmology.py	Adds the new CosmologyWithOmegaM protocol and removes HasOmegaM from the base Cosmology protocol.
glass/shells.py	Narrows DensityWeight.cosmo to CosmologyWithOmegaM and updates the attribute docstring accordingly.
tests/core/test_shells.py	Updates test_density_weight to require a cosmology object that supports Omega_m.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

glass/shells.py:153

• Renaming the dataclass field from cosmo to cosmo_omega_m changes the public constructor/attribute API (e.g., existing DensityWeight(cosmo=...) calls would break) and is inconsistent with the other weight classes in this module which all use cosmo. It should remain cosmo and only the type should be narrowed to CosmologyWithOmegaM. Also, the __call__ docstring currently says “comoving distance” even though this class is a density weight.

    cosmo_omega_m: CosmologyWithOmegaM

    def __call__(self, z: FloatArray) -> FloatArray:
        """
        Uniform weight in comoving distance.