IPv6 zones handling & Unicode control characters fixes

Added

DocC Documentation

EmailSyntaxValidator: Class-level documentation with usage examples
Mailbox: Struct and property documentation (email, localPart, host)
LocalPart/Host enums: Case documentation for dotAtom, quotedString, domain, addressLiteral
Options enum: Documentation for autoEncodeToRfc2047 option
Compatibility enum: Detailed documentation for ascii, asciiWithUnicodeExtension, unicode modes
RFC2047Coder: Class documentation with encoding examples, encode() and decode() method documentation
IPAddressSyntaxValidator: Class documentation explaining RFC 5321 context
New Unit Tests

48 new tests covering edge cases, Unicode handling, RFC2047 encoding, and IP address validation
Test coverage for boundary conditions, security scenarios, and RFC compliance
Fixed

RFC 5321 Compliance

IPv6 zone identifiers (e.g., fe80::1%eth0) are now correctly rejected per RFC 5321 Section 4.1.3
RFC 5198 Compliance

C1 control characters (U+0080-U+009F) are now rejected in Unicode mode
RFC 6531 Compliance

Fixed supplementary Unicode plane support (U+10000-U+10FFFF) - emoji and characters beyond BMP now validate correctly
Security Improvements

Bidirectional formatting characters are now rejected to prevent homograph attacks:
LRM/RLM (U+200E-U+200F)
Directional embeddings/overrides (U+202A-U+202E)
Directional isolates (U+2066-U+2069)
Deprecated format characters (U+206A-U+206F)
Changed

Reordered CharacterSet construction to work around Foundation bug with supplementary Unicode planes

Security Review Report: SwiftEmailValidator

Summary

No high-confidence security vulnerabilities were identified in the SwiftEmailValidator codebase.

Analysis Scope

The following areas were examined:

Category	Files Analyzed	Result
Regular Expression (ReDoS)	IPAddressSyntaxValidator.swift, RFC2047Coder.swift	Safe - bounded repetition, no exponential backtracking
Unicode Security	EmailSyntaxValidator.swift	Strong controls - blocks bidi overrides, control chars
Base64/QP Decoding	RFC2047Coder.swift	Robust input validation, length limits enforced
Injection Vulnerabilities	All source files	No SQL, command, template, or path injection vectors
Data Exposure	All source files	No logging, persistence, or side effects
Input Validation	All source files	Comprehensive limits and edge case handling

Key Security Controls Observed

1. Input Length Limits: Local part capped at 64 chars, RFC2047 input at 76 chars
2. Unicode Filtering: Blocks C1 control characters, bidi formatting chars, deprecated format chars
3. Pure Validation: No network access, file I/O, or shell execution
4. Charset Whitelisting: Only accepts utf-8, utf-16, utf-32, iso-8859-1, iso-8859-2

Findings

None - No vulnerabilities met the >80% confidence threshold for reporting.