Add type hints to all code base

[juanitorduz]

Add type hints to all code base following on #556

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📚 Documentation preview 📚: https://causalpy--557.org.readthedocs.build/en/557/

[codecov]

Codecov Report

❌ Patch coverage is 95.41284% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.52%. Comparing base (f918e84) to head (6034cb3).

Files with missing lines	Patch %	Lines
causalpy/pymc_models.py	87.50%	3 Missing ⚠️
causalpy/data/simulate_data.py	80.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             mypy     #557      +/-   ##
==========================================
- Coverage   95.54%   95.52%   -0.03%     
==========================================
  Files          29       29              
  Lines        2695     2705      +10     
==========================================
+ Hits         2575     2584       +9     
- Misses        120      121       +1     

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[Copilot]

Pull Request Overview

This pull request adds comprehensive type hints to the entire CausalPy codebase, following up on PR #556. The changes improve code maintainability and enable better static type checking.

Key Changes:

• Added type annotations to function parameters and return types across all modules
• Updated type hint syntax to use modern Python union syntax (X | None instead of Optional[X])
• Added type hints to experiment classes, model classes, and utility functions

Reviewed Changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 27 comments.

Show a summary per file

File	Description
docs/source/_static/interrogate_badge.svg	Updated documentation coverage badge from 95.8% to 95.1%
causalpy/utils.py	Added type hints to utility functions including round_num, _format_sig_figs, and convert_to_string
causalpy/skl_models.py	Added type hints to scikit-learn model adaptor classes and methods
causalpy/pymc_models.py	Added comprehensive type hints to PyMC model classes including LinearRegression, InstrumentalVariableRegression, and PropensityScore
causalpy/plot_utils.py	Updated type hints in plotting utility functions using modern union syntax
causalpy/experiments/synthetic_control.py	Added type hints to synthetic control experiment class methods
causalpy/experiments/regression_kink.py	Added type hints to regression kink experiment class methods
causalpy/experiments/regression_discontinuity.py	Added type hints to regression discontinuity experiment class methods
causalpy/experiments/prepostnegd.py	Added type hints to pre-post NEGD experiment class methods
causalpy/experiments/inverse_propensity_weighting.py	Added type hints to inverse propensity weighting experiment class methods
causalpy/experiments/interrupted_time_series.py	Added type hints to interrupted time series experiment class methods
causalpy/experiments/instrumental_variable.py	Added type hints to instrumental variable experiment class methods
causalpy/experiments/diff_in_diff.py	Added type hints to difference-in-differences experiment class methods
causalpy/experiments/base.py	Added type hints to base experiment class including abstract methods
causalpy/data/simulate_data.py	Added comprehensive type hints to all data simulation functions

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[drbenvincent]

Approving. Assuming this is auto run remotely as part of the pre-commit checks? As in, we don't need to add to the GitHub actions?

[juanitorduz]

Exactly, I will rebase and merge