sorts: type cocktail shaker sort for comparable items

[ElenaGe216]

Part of #15234

Describe your change

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

Summary

Type cocktail_shaker_sort for mutually comparable values instead of only integers. The implementation is unchanged; its signature now preserves the element type, its doctest records the mixed-type TypeError contract, and the existing shared rejection test now covers it.

Testing

• python3 -m doctest -v sorts/cocktail_shaker_sort.py: 8 passed
• uvx pytest sorts/cocktail_shaker_sort.py tests/test_sorts.py --doctest-modules: 231 passed
• uvx ruff check and uvx ruff format --check: passed
• uvx ty check sorts/cocktail_shaker_sort.py: passed
• uvx pre-commit run --all-files: passed

Checklist

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• This PR uses a closing keyword for sorts: make algorithms sort any comparable items, not just ints #15234. This is intentionally unchecked because sorts: make algorithms sort any comparable items, not just ints #15234 is a tracking issue that must remain open until all algorithms are completed.