Fix Tree Sort algorithm for duplicate values and input types

[lighting9999]

Describe your change:

1. Fixed duplicate value handling:

   • Modified BST insertion to accept values <= current node to left subtree
   • Ensures duplicate values appear in sorted order

2. Enhanced input type support:

   • Function now accepts both lists and tuples as input
   • Added type annotation: arr: list[int] | tuple[int, ...]

3. Improved empty input handling:

   • Returns empty tuple immediately for empty input
   • More efficient than building BST

4. Added comprehensive documentation:

   • Complete docstring with examples and edge cases
   • Detailed comments explaining BST traversal and insertion
   • Explicit test case for duplicate values

5. Optimized variable naming:

   • items = list(arr) for clarity
   • Removed unused len method

6. Maintained all original functionality:

   • Still returns sorted tuple
   • Preserves BST sorting algorithm
   • Passes all original tests plus new tests for duplicates

All pre-commit checks pass:

• ruff (linting and formatting)
• mypy (type checking)
• codespell (spelling)
• doctests

• 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?

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 new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• 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.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".