lex_kinds.nx

lex_kinds.nx -- alias stub. Migration to nx_-prefixed canonical name. Consumers via "import \"lex_kinds.nx\"" resolve to nx_lex_kinds.nx through NishiLang's textual import splicing with path dedup (runtime/import.nx I1). Eliminates duplicate-symbol errors when both names appear in the transitive import tree (e.g., nxc.nx imports lex_kinds.nx directly AND nx_regalloc.nx imports nx_lex_kinds.nx). Deprecation: delete this stub when every "lex_kinds.nx" consumer has migrated to "nx_lex_kinds.nx".