Description of Change

Improved the existing jump_search.cpp implementation:

• Precomputed sqrt(n) once before the loop instead of recomputing
  on every iteration — avoids repeated floating point operations
• Replaced raw int[] array with std::vector<int> (modern C++)
• Used static_cast<int> for float-to-int conversion (safer than implicit cast)
• Added complete Doxygen documentation (\brief, \param, \returns)
• Added self-test suite covering:
  • Element in middle
  • First element
  • Last element
  • Element not present
  • Below range
  • Single element array
  • Empty array

Time complexity: O(sqrt(n)) — unchanged
Space complexity: O(1) — unchanged

Relates to #2456

Checklist

• Added description of change
• Added file name matches File name guidelines
• Added tests and example, test must pass
• Added documentation so that the program is self-explanatory and educational - Doxygen guidelines
• Relevant documentation/comments is changed or added
• PR title follows semantic commit guidelines
• Search previous suggestions before making a new one, as yours may be a duplicate.
• I acknowledge that all my contributions will be made under the project's license.