IPv6 Address Normalization

Summary

Implement IPv6 address normalization for comparison.

Requirements

• Lowercase hex digits
• Compress consecutive zero groups
• Expand compressed addresses for comparison
• Normalize zone IDs

Example

// These should be equivalent after normalization:
"[2001:0db8:0000:0000:0000:0000:0000:0001]"
"[2001:db8::1]"
"[2001:DB8::1]"

Acceptance Criteria

• Equivalent addresses compare as equal
• Canonical form output
• Tests with various formats