[AdamMagued]

Fixes #427

Summary

• Enable embedded structs inside dig.In parameter objects and dig.Out result objects.
• Unpack embedded structs that either embed dig.In/dig.Out or contain exported fields without explicit parameter/result tags (name, group, optional), preserving concrete value dependency semantics for tagged embeds or structs without exported fields.
• Propagate ignore-unexported settings to embedded parameter structs.
• Handle nested soft value groups during parameter object resolution.
• Enforce validation against invalid tags (name, group) on embedded result objects and disallow cross-embedding (dig.In in dig.Out or vice versa).
• Add unit tests covering embedding scenarios, tag propagation, nested levels, and validation errors.