feat: VersionIcon fixes and improvements

[DanielCech]

Summary

Modernizes VersionIcon to work with real asset catalogs instead of a hardcoded legacy icon list, adds configurable error handling with --onError fail|warn, and refactors the implementation into smaller support files for maintainability.

Changes

• Discover and process icon variants from Contents.json dynamically
• Resolve Info.plist and icon asset paths more reliably across projects
• Add --onError fail|warn to allow non-blocking builds when desired
• additional parameter --titleRotation.
• new --versionStyle values
• Improve test coverage, including a Flashcards-style asset catalog case
• Split the old monolithic implementation into focused support files

Verification

• swift test passes