Add type hints to methods in custom_loggers.py

[Sidhant185]

Describe your changes

Add str, Optional[int], list and None return type hints to all method
signatures and return types in neural_lam/custom_loggers.py.

Methods updated:

• CustomMLFlowLogger.__init__
• CustomMLFlowLogger.save_dir
• CustomMLFlowLogger.log_image

No logic changes were made — only type annotations were added.

Issue Link

closes #454

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
• 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
• I have requested a reviewer and an 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:
  • maintenance: add type hints to methods in custom_loggers.py

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 com

[kshirajahere]

Only Optional is actually used in this file now. Dict and Any are unused imports.