fix: raise ValueError for zero input in binary_count_trailing_zeros

[kasc0206]

Description

Fixes #14479

The binary_count_trailing_zeros function previously returned 0 for input a == 0, but mathematically the number of trailing zeros in the binary representation of 0 is undefined (infinite). Returning 0 was misleading and could cause bugs in algorithms relying on correct trailing zero counts.

Changes

• Changed if a < 0 to if a <= 0 to catch zero input
• Removed the 0 if (a == 0) else ternary fallback
• Updated doctest for binary_count_trailing_zeros(0) to expect ValueError
• Updated string-input doctest error message from '<' to '<='

Verification

• ✅ doctest: 9/9 tests passed
• ✅ ruff: All checks passed
• ✅ mypy: No issues found

[algorithms-keeper]

Closing this pull request as invalid

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