I'm creating an extremely challenging regex challenge that combines a wide variety of advanced matching tasks in a single text sample. This sample includes a quoted email-like string with a literal IPv6 domain, an international phone number with an extension and irregular spacing, a date/time format with slashes, fractional seconds, and a nonstandard timezone, a deeply nested structure mixing multiple types of brackets, a JSON-like object with escaped quotes and nested arrays, a verbose regex pa... (truncated)