Track generated files and run-artifact outputs

[godofecht]

Problem

Generated-source workflows are central to large Zig projects. Azazel has pre commands, but replacement parity needs generated output tracking.

Needed

• Model run artifacts that produce files.
• Attach generated outputs to module source/import/include paths.
• Support generated version files, protocol translations, manpage generation, and table generation.
• Make output paths explicit in generated build_spec.zig.

Corpus drivers

• ZLS generated version data.
• River generated protocol modules.
• libxev generated pkg-config/manpage-style outputs.
• libvaxis generated Unicode tables through uucode_generate.

Done when

• A generated file can be declared in project.cue, produced before compile, and consumed by a module.
• tools/huge_corpus.py --parity --repo libvaxis can validate a generated-output target slice.