Enable mypy type checking in pre-commit hooks

[dhalperi]

This PR enables mypy type checking in the pre-commit hooks configuration.

Changes

• Add mypy hook using the mirrors version for CI compatibility
• Include all necessary dependencies for proper type checking
• Configure mypy to run on src/ directory only
• Use pass_filenames: false to avoid module resolution issues

Benefits

• Type safety: Catch type-related bugs before they reach the main branch
• CI integration: Works seamlessly in GitHub Actions and other CI environments
• Developer experience: Automatic type checking on every commit
• Code quality: Maintains strict typing standards established in pyproject.toml

Technical Details

• Uses repo: https://github.com/pre-commit/mirrors-mypy for CI compatibility
• Includes comprehensive additional_dependencies list for all project imports
• Configured with args: [src/] and pass_filenames: false to handle package structure correctly
• Runs mypy v1.18.1 with strict type checking settings from pyproject.toml

Testing

• ✅ All 138 source files in src/ pass mypy type checking
• ✅ All pre-commit hooks work together successfully
• ✅ Configuration tested locally and ready for CI

The test files in tests/ have 126+ type issues that would require significant refactoring, so they are excluded for now but could be addressed in a future PR.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.57%. Comparing base (65c3867) to head (22ac2ac).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #89   +/-   ##
=======================================
  Coverage   83.57%   83.57%           
=======================================
  Files          86       86           
  Lines        3902     3902           
=======================================
  Hits         3261     3261           
  Misses        641      641           

Flag	Coverage Δ
unittests	83.57% <ø> (ø)

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