fix(searches): jump_search returns -1 for empty list (was IndexError)

[sudo-ai-git]

Fixes #15085

jump_search([], 5) raised IndexError because arr[min(step, arr_size) - 1] evaluates arr[-1] on an empty collection.

Change: early return -1 when the collection is empty (an empty sequence cannot contain the target), + doctest to lock the behavior.

Verified: doctest passes (6 tests incl. the new empty case); jump_search([], 5) == -1, normal cases unaffected.

[algorithms-keeper]

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