I'm creating an extremely challenging regex match challenge that spans multiple complex formats: a highly-complex email, international phone numbers with both parentheses and dashes, multiple date formats with varying separators, both IPv4 and abbreviated IPv6 addresses, a UUID, a Base64 encoded string, an HTML snippet with escaped quotes, a multi-line code snippet, a regex pattern with backreferences, a deeply nested URL with query parameters and an anchor, and finally an advanced regex pattern... (truncated)