Function serialize 

pub fn serialize(reg: &SchemaRegistry) -> String

Serialize a reconciled registry to bynk.schema.lock’s TOML form — what bynk-driver writes to disk, atomically, only on a fully clean build (compile_project’s own gate). No disk access here; see this module’s doc comment for why. Cannot fail for this data shape (string keys, no floats) — toml::to_string_pretty only errors on inputs this struct never produces.