refactor: rename d_mesh_static dimension to num_mesh_static_vars

[uttam12331]

Describe your changes

Rename the mesh-node static-feature dimension d_mesh_static to
num_mesh_static_vars in comments and docstrings, so the name matches the
canonical num_* naming used across the codebase (as agreed in the #635
review). This is a naming/documentation change only — no runtime behaviour is
altered.

The README dimension list and the broader N_mesh cleanup are intentionally
left out of scope: the README list arrives with #635 (still open), and keeping
this PR to a single concern was requested in review.

No new dependencies.

Issue Link

closes #687

Type of change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📖 Documentation (Addition or improvements to documentation)

Checklist before requesting a review

• My branch is up-to-date with the target branch
• I have performed a self-review of my code
• For any new/modified functions/classes I have added docstrings that clearly describe its purpose, expected inputs and returned values
• I have placed in-line comments to clarify the intent of any hard-to-understand passages of my code
• I have updated the README to cover introduced code changes — N/A: the README dimension list is intentionally out of scope and tracked in feat: add optional boundary datastore support #635
• I have added tests that prove my fix is effective or that my feature works — N/A: comment/docstring-only rename; existing tests pass unchanged
• I have given the PR a name that clearly describes the change, written in imperative form
• I have requested a reviewer and an assignee — N/A: no write access; maintainers tagged

Checklist for reviewers

• the code is readable
• the code is well tested
• the code is documented (including return types and parameters)
• the code is easy to maintain

Author checklist after completed review

• I have added a line to the CHANGELOG describing this change, in the maintenance section

Checklist for assignee

• PR is up to date with the base branch
• the tests pass
• (if the PR is not just maintenance/bugfix) the PR is assigned to the next milestone. If it is not, propose it for a future milestone.
• author has added an entry to the changelog (and designated the change as added, changed, fixed or maintenance)
• Once the PR is ready to be merged, squash commits and merge the PR.

[sadamov]

Thanks @uttam12331, the rename is clean and complete: d_mesh_static is gone everywhere and num_mesh_static_vars matches the num_* family we agreed in the #635 review. Good call leaving the README and the N_mesh cleanup out of scope too, the README list arrives with #635 (still open) and keeping this to one concern is right.

One change needed before merge: please add a CHANGELOG entry. It is mandatory for every PR), and a doc/comment rename fits the ### Maintenance section:

- Rename the `d_mesh_static` mesh-node static-feature dimension to `num_mesh_static_vars` in comments and docstrings, matching the canonical `num_*` naming. [\#695](https://github.com/mllam/neural-lam/pull/695) @uttam12331

Two notes on our contributing flow for next time, not specific to the code here:

• Please comment on the issue and get it assigned before opening a PR, so we avoid duplicate effort. #687 already had another interested contributor, and commenting first keeps it clear who is on it.
• Please fill in the PR template in full (.github/pull_request_template.md) rather than a free-form description. The content you wrote is good, it just needs to live in the template sections.

Let me know once the CHANGELOG is in and I will re-review.

[uttam12331]

Thanks for the review @sadamov! Added the CHANGELOG entry under ### Maintenance as suggested. Ready for re-review. Noted on the issue-assignment and PR-template flow for next time.

[joeloskarsson]

Please fix the PR template.

[uttam12331]

Thanks @joeloskarsson — updated the PR description to follow the template (filled in the change summary, linked closes #687, marked it as Documentation, and noted the CHANGELOG maintenance entry). Let me know if anything else is needed.

[sadamov]

@uttam12331 the PR-template is still cut off. Please be especially careful when using agents, as these tend to mess with the template.

[uttam12331]

Thanks for the patience @sadamov — the template was cut off (missing the Checklist for reviewers and Checklist for assignee sections). Both are now included in full. Ready for re-review.