[devam007]

Description of Change

Return -1 for n <= 0 before jump search reads the array. Previously, a zero-sized
step could read arr[-1] and even return a match for a logically empty range.
Add assertions for empty input, null with zero length, singletons, duplicates,
end-position matches and absent targets. Retain the existing example.

Validation

GCC 15.2 / C++17: 41,311 focused reference comparisons pass against
std::binary_search with seeded sorted inputs and boundary targets. A safe backing-
array reproduction returns an incorrect match on the base and -1 with the fix.
Warning-enabled compilation with libstdc++ assertions, the CMake/Ninja target,
the source assertions and git diff --check pass. Remote CI, clang-format and
clang-tidy were not run locally.

• Read contribution guidelines and kept the change to one algorithm file
• Added regression assertions and verified the existing example
• Reviewed the patch for unrelated changes

Related prior work: #3169 included empty-input handling in a broader vector/API rewrite and was closed unmerged after inactivity. This patch keeps the existing array API and limits the change to the boundary guard and regression assertions.