Build-script glue

Build helper requirements for Build-script glue (FEAT_0083) — wiring the parser and codegen into a consuming crate’s build.rs.

Feature: Build-script glue FEAT_0083
status: open
satisfies: FEAT_0080
is satisfied by: REQ_0830, REQ_0831

A build.rs helper that wires the parser and codegen into a consuming crate’s build, emitting the generated module into OUT_DIR.
Requirement: Generate into OUT_DIR for include REQ_0830
status: open
satisfies: FEAT_0083
is verified by: TEST_0839

The build helper shall read the configured network.yaml, run parse + codegen, and write one Rust module into OUT_DIR for the consumer to pull in via include!(concat!(env!("OUT_DIR"), "/network.rs")). The generated module shall not be checked into version control.
Requirement: Rebuild on config or ESI change REQ_0831
status: open
satisfies: FEAT_0083
is verified by: TEST_0840

The build helper shall emit cargo:rerun-if-changed directives for the network.yaml and every vendored ESI file it resolves, so a change to topology or a referenced device description triggers regeneration.