feat: Enable comprehensive mypy type checking across landmarkdiff codebase

[PredictiveManish]

What does this PR do?

Enable comprehensive mypy type checking across the LandmarkDiff codebase by updating configuration, CI/CD pipeline, and adding package init.py files to enable type checking on scripts/ and benchmarks/ directories.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• New procedure preset
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Tests / CI improvement

How has this been tested?

mypy landmarkdiff/
mypy scripts/__init__.py
mypy benchmarks/__init__.py

Checklist

• My code follows the project's style guidelines (ruff check passes)
• I have added tests that cover my changes
• All new and existing tests pass locally
• I have updated documentation if needed
• My changes generate no new warnings

Related Issues

Solves #410

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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