install-skills copies the skills/ tree from the managed helper checkout
into the user's agent skills directory.
Each skill is a directory containing a SKILL.md whose YAML frontmatter
carries a required name field. That name is the discovery name a strict
loader uses; a manifest without it is not discoverable.
Each shipped skill directory matches its manifest name, so a skill can be
referred to by the same identifier on disk and at the point of discovery.
Codex presents only a short prefix of each skill description during discovery. Shipped descriptions therefore use one purpose-led sentence of at most 120 characters. The sentence identifies the user task, the distinctive technology or artefact, and any boundary needed to distinguish neighbouring skills. Detailed triggers, versions, commands, and procedures live in the skill body, which the agent loads only after selecting the skill.
make lint validates every shipped manifest, so a malformed or non-conformant
manifest cannot be installed.