Schema types for roam RPC service definitions.

Design Philosophy

This crate uses facet::Shape directly for type information rather than defining a parallel type system. This means:

• No TypeDetail — We use &'static Shape from facet instead
• Full type introspection — Shape provides complete type information
• Zero conversion overhead — Types are described by their Shape directly

For type-specific queries (is this a stream? what are the struct fields?), use the facet_core API to inspect the Shape.