See docs/testing.md — how to test a change to linux-pkg itself, how CI for a
package works, and how to use linux-pkg to build/validate a change made in one of the many
packages it orchestrates.
A change to a tool, option, mode, job, or package list — or a newly found (or fixed) gotcha —
should update docs/testing.md. If this repo ever gains a second AI-agent instruction file (e.g.
.github/copilot-instructions.md, which does not exist today), carry this same testing-doc
pointer into it too; nothing keeps two such files in sync automatically.