I'm creating an extremely difficult challenge that pushes regex techniques to the limit. This challenge integrates a mix of advanced pattern types: an email address with a quoted local part and an IPv6 domain; an international phone number including an optional area code and extension; ISO8601 date-time formats with varying separators and milliseconds; nested and balanced grouping with mixed delimiters; product codes with Greek characters; version strings with pre-release and build metadata; a s... (truncated)