feat: add binary search on answer template with example use case

[meenaksh06]

Describe your change:

• [x ] Add an algorithm
• Fix a bug or typo in an existing algorithm
• Add or change doctests
• Documentation change

Improved the existing Binary Search on Answer implementation by:

• Adding comprehensive doctests to validate correctness
• Covering important edge cases (boundary conditions, monotonic checks)
• Ensuring all doctests pass successfully with automated testing

These changes improve reliability and make the implementation easier to understand and verify.

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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.
• 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.

[algorithms-keeper]

Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

• Contributing guidelines
• Project Euler solution guidelines

Python:

• Formatted string literals (f-strings)
• Type hints
• doctest
• unittest
• pytest

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.

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[algorithms-keeper]

As there is no test file in this pull request nor any test function or class in the file searches/binary_search_on_answers.py, please provide doctest for the function can_ship