feat: add Comb Sort algorithm

[Samuelf27]

Description

Adds the Comb Sort algorithm to sorts/.

Comb sort is an improvement over bubble sort: instead of always comparing adjacent elements, it compares elements separated by a gap that starts large and shrinks each pass by a factor of ~1.3. This quickly moves small values stuck near the end (so-called "turtles") toward the front, giving much better practical performance than bubble sort while staying simple and in-place.

• Average / worst time complexity: O(n^2 / 2^p) (where p = number of increments) → close to O(n log n) in practice, O(n^2) worst case
• Space complexity: O(1) (in-place)

Checklist

• New algorithm implementation under sorts/comb_sort.ts
• Tests added under sorts/test/comb_sort.test.ts (empty, sorted, reverse, duplicates, random)
• Follows the repository style (JSDoc header, named export) and passes Prettier
• Self-reviewed the code