Fix anagram finder

[dimaush]

Изменил логику решения: дубликаты теперь не считаются (кажется, это более логично, чем считаются).

Также внёс разные стилистические правки.

[vtm9]

Closing after review: the existing task explicitly allows duplicate words, and its solution and asserts consistently implement that contract. This PR intentionally changes that rule to deduplication, changing valid answers such as ["a", "a"] from [["a", "a"]] to the no-anagrams sentinel. There is no demonstrated defect in the original behavior, so this is an unsupported task-rule change rather than a fix. Formatting and naming cleanups can be proposed separately while preserving the contract.