Added

• Slovak (sk) language support with built-in stop words, SlovakStemmer, analyser-factory registration, and tests (0e803c74, e820f0c1), contributed by Jozef Gajdoš (@harrison314).

Fixed

• LowercaseFilter now lowercases non-ASCII uppercase characters such as Č, Š, and Ž in both buffer and span-token paths. Reported by Jozef Gajdoš (@harrison314) in #50.