Function generate_schema_rs 

pub fn generate_schema_rs(state: &ArchitectureState) -> String

Generate schema.rs for a common crate (no @generated header).

Emits only the portable data-contract layer: value structs, key enums, SchemaType and Linkable impls. No configure_schema, no runtime deps. This keeps the common crate platform-agnostic (no_std-compatible).