Add Byte Type Support

[j-d-ha]

Priority: P3 - Nice to have
Tier: 4 - Polish
Effort: Small (2-3 hours)

Already In Codebase

• There are scalar extension methods for numeric types (int/long/float/double/decimal), bool, string, DateTime/Offset/TimeSpan, Guid, enums.
• There is currently no byte / byte? support in runtime extensions or generator type mapping.

Goal

Add support for byte and byte? mapping.

Implementation notes

• Runtime:
  • Add GetByte / GetNullableByte and SetByte methods (likely in NumericAttributeValueExtensions), using CultureInfo.InvariantCulture.
• Generator:
  • Add byte type mapping in TypeMappingStrategyResolver.
• Tests:
  • Add generator verify tests covering byte and nullable byte.

Acceptance criteria

• Byte properties are mapped correctly and tested.