Element Patterns are not implemented

This is a hard one as a basic regex parser needs to be included for checking and to create a Restricted Character Set.

Current Behavior - Logs a debug message but doesn't fail

✅ Grammar generation continues (error is commented out)
⚠️ Pattern is parsed but not enforced
⚠️ No validation happens at encode/decode time

1. Character set can help make encoding smaller
2. Runtime evaluation `strict mode`