Code Generation
From build_spec.zig to build.zig
build_spec.zig contains typed constants for toolchain lanes, packages, options,
and modules. build.zig imports it at comptime, rejects unsupported Zig lanes,
creates std.Build.Module values, applies native/options/package/generated
metadata, creates only the artifacts that need independent compilation, wires
import or ABI edges, and attaches install/post-build steps.
This executor is where Zig-version API adaptation belongs. Keeping that logic centralized is the main compatibility value Azazel offers consuming projects.