YARA rule validator

It parses the rule file the way YARA reads it: imports, includes, global and private rules, tags, meta, text and hex and regex strings with their modifiers, and the condition section. Syntax problems it reports are the ones a yarac compile would reject first, and the slow-pattern warnings cover the classic atom killers: text under four bytes, hex that is mostly wildcards, wide jumps, and regexes without a literal prefix. It does not compile the rule with libYARA, does not fully expression-parse conditions, does not scan any file, and never fetches an include target; includes are listed so you can paste them in yourself.