perf(strings): optimize anagram signature using frequency counts (#12927) * fix(strings): use frequency-based signature for anagrams Replaced the sorting-based signature implementation with a frequency-based approach using `collections.Counter`. This ensures that the signature represents both characters and their counts, preventing collisions and better grouping of true anagrams. Examples: - "test" → "e1s1t2" - "finaltest" → "a1e1f1i1l1n1s1t2" - "this is a test" → " 3a1e1h1i2s3t3" Also updated the anagram lookup to use the new frequency-based signatures, making results more accurate and avoiding false positives. * Refactor anagram function return type to list[str] * Update anagrams.py * Update anagrams.py * Update anagrams.py * Update anagrams.py * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci --------- Co-authored-by: Maxim Smolskiy <mithridatus@mail.ru> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>