Macro build 

macro_rules! build {
    ($file:expr) => { ... };
}

Embed the shared Canic configuration into a canister crate’s build script.

Reads the provided TOML file (relative to the crate manifest dir), validates it using the shared config schema, and emits both a compact source copy and a generated Rust config model for runtime bootstrap. Canister crates typically invoke this from build.rs.