Unicode Normalization for IRIs

Summary

Implement Unicode normalization for IRI comparison.

Background

IRIs should be normalized using NFC (Canonical Decomposition, followed by Canonical Composition) before comparison.

Requirements

• NFC normalization for IRI components
• Case folding for comparison (where appropriate)
• Handle combining characters

Acceptance Criteria

• Equivalent IRIs compare as equal
• Tests with combining characters
• Tests with precomposed vs decomposed forms