Expose homeModules.default, a home-manager module whose programs.agents.skills
option places operator-selected skill derivations into Claude Code's skills
directory, one recursive home.file per skill, gated on programs.claude-code.enable
and sourcing configDir from the claude-code module. Add a nix flake check that
builds the home-files tree under several operator configurations and asserts
placement, recursion, the enable gate, configDir sourcing, and coexistence with
an operator's own skills.
Add the content tier: a standalone flake that auto-discovers each skill
(a directory containing a SKILL.md, at any depth) and exposes it as an
individually addressable derivation built by lib.mkSkill. Directories
without a SKILL.md are descended through as cosmetic containers; once a
SKILL.md is found, that directory's subfolders are its assets, not
further skills. Skill names must be globally unique across the tree — a
collision is a hard eval-time error, not a warning.
A fixture-driven skill-build check under `nix flake check` exercises the
recursive walk, the builder, the SKILL.md-at-$out-root contract, the
eval-time name passthru, and the collision error. The repo ships no real
skill content yet, so packages.<system> is empty today.
