Fix out-of-range recursion in interpolation_search_by_recursion

[RizgarOzan]

Describe your change

interpolation_search_by_recursion never checks that left <= right (the iterative interpolation_search does, via its while loop), so an item just above the last element, an empty list, or a range reversed by the point > right branch crashes instead of returning None:

>>> interpolation_search_by_recursion([0, 5, 7, 10, 15], 16)
IndexError: list index out of range
>>> interpolation_search_by_recursion([], 1)
IndexError: list index out of range
>>> interpolation_search_by_recursion([0, 3, 6, 12, 14, 15, 20], 10)
RecursionError: maximum recursion depth exceeded

This adds the missing bounds guard. The equal-ends branch is collapsed into a single return to stay within ruff's PLR0911 limit. New doctests cover the three crashing cases plus the symmetric below-minimum case; they fail on master (3 failures) and pass with the fix (python -m doctest -v: 21 passed). A 200k-case random comparison against a brute-force search now passes for both functions. ruff check, ruff format --check, ty check and pre-commit on the file are clean.

• 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".

[cclauss]

ON HOLD: Our focus is on merging or closing old pull requests before October 1st.

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