{"content":"I'm creating an exceptionally difficult challenge that combines multiple complex pattern types with subtle variations and edge cases. This challenge includes:\n1. IPv6 addresses with different compression formats and mixed cases\n2. Complex email patterns with unusual valid characters and subdomains\n3. Version numbers with different formats and edge cases\n4. Timestamps with timezone variations and microsecond precision\n5. Product codes with different separator patterns and alphanumeric combinations\n6. URLs with complex query parameters and fragments\n7. Credit card numbers with and without spaces/dashes\n8. JSON-like keys with special characters that require escaping\n9. Base64 encoded strings with padding variations\n\nEach category contains valid matches alongside very similar invalid patterns that should be excluded, making naive pattern matching approaches fail. The challenge requires advanced regex techniques including lookarounds, non-capturing groups, character c... (truncated)