Leetcode 591. Tag Validator

Validate whether a string is a single correctly wrapped XML-like code snippet by parsing tags, CDATA blocks, and text to ensure tags are properly nested and closed. This requires checking tag-name rules (1–9 uppercase letters), handling <![CDATA[...]]> blocks as raw text, and detecting malformed or unmatched '<'/'>' and start/end tags (typically via a stack-based nesting check).