Add comprehensive type hints to vis.py (closes #624)

[GiGiKoneti]

Describe your changes

Added comprehensive static type hints to the visualization suite to improve mypy coverage and static analysis.

• neural_lam/vis.py: Added explicit typing for all core plotting functions (plot_on_axis, plot_error_map, plot_prediction, plot_spatial_error), correctly typing xr.DataArray, torch.Tensor, and matplotlib.figure.Figure.
• Explicitly imported necessary matplotlib sub-modules (axes, figure, collections) to prevent runtime AttributeError when evaluating static types.

No new dependencies are required for this change.

Issue Link

closes #624

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 - if not update your fork with the changes from the target branch (use pull with --rebase option if possible).
• 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
• I have added tests that prove my fix is effective or that my feature works
• I have given the PR a name that clearly describes the change, written in imperative form (context).
• I have requested a reviewer and an assignee (assignee is responsible for merging). This applies only if you have write access to the repo, otherwise feel free to tag a maintainer to add a reviewer and assignee.

Checklist for reviewers

Each PR comes with its own improvements and flaws. The reviewer should check the following:

• 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 a section
  reflecting type of change (add section where missing):
  • added: when you have added new functionality
  • changed: when default behaviour of the code has been changed
  • fixes: when your contribution fixes a bug
  • maintenance: when your contribution is relates to repo maintenance, e.g. CI/CD or documentation

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.

[kshirajahere]

Left two comments for now which I had a look over just before going to bed. If i find any other improvements/changes will ping :)

[GiGiKoneti]

@kshirajahere @sadamov
Is there anything I should add or improve here ?
I guess I'hv covered the most.

[GiGiKoneti]

@sadamov
[CPU+GPU testing / tests (uv, gpu) (pull_request)]Cancelled after 1440m
it was stuck in queue for hours , please consider re-running the checks.