dev: fix some mypy errors and switch to ruff

[jrycw]

Hello team,

I ran mypy on our codebase and resolved around 60 reported errors in this PR (leaving 300+ errors still to address). Most of the changes involve refining type hints.

Based on my observations, mypy seems to struggle with the following scenarios:

• Redefining a variable within the same scope while changing its type.
• Fully understanding the logic behind our DataFrame backend.
• Recognizing that GTSelf is a TypeVar for GTData, which causes many GT attributes to be flagged as "not found."
• Handling returned values that might include None, which can be challenging to annotate correctly.

Feel free to accept, reject, or modify anything in this PR.

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 9 lines in your changes missing coverage. Please review.

Project coverage is 89.71%. Comparing base (538fbf1) to head (019f637).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
great_tables/_export.py	25.00%	3 Missing ⚠️
great_tables/_formats.py	50.00%	2 Missing ⚠️
great_tables/_body.py	50.00%	1 Missing ⚠️
great_tables/_gt_data.py	96.42%	1 Missing ⚠️
great_tables/_utils.py	96.66%	1 Missing ⚠️
great_tables/gt.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #511      +/-   ##
==========================================
+ Coverage   89.38%   89.71%   +0.32%     
==========================================
  Files          45       45              
  Lines        5239     5202      -37     
==========================================
- Hits         4683     4667      -16     
+ Misses        556      535      -21     

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[machow]

Thanks so much for stripping so much dead code and fixing types. We're working on completing a pyopensci review for Great Tables, which recommended linting for unused imports (pyOpenSci/software-submission#202 (comment)).

I think we disabled unused imports and unused variables from our linter, when we did a very early refactor. Rich and I are going to pair tomorrow to re-enable more linting rules, so we can stick to the level of quality in this PR 😅. If it's okay, we'll just add to this PR and then merge.

[jrycw]

Thanks so much for stripping so much dead code and fixing types. We're working on completing a pyopensci review for Great Tables, which recommended linting for unused imports (pyOpenSci/software-submission#202 (comment)).

I think we disabled unused imports and unused variables from our linter, when we did a very early refactor. Rich and I are going to pair tomorrow to re-enable more linting rules, so we can stick to the level of quality in this PR 😅. If it's okay, we'll just add to this PR and then merge.

Wow, that’s great! It’s exciting to see so many valuable suggestions for this project. Personally, I’d recommend we clean up the issues—for example, closing those that have already been addressed or answered.

[rich-iannone]

LGTM!