- Remove dead overlays/default.nix (flake defines overlays inline)
- Remove orphaned overlays/mods/{beads,n8n}.nix (never imported)
- Remove docs/packages/notesmd-cli.md (package doesn't exist)
- Extract externalSkills submodule to shared-options.nix (eliminates
~100 lines of duplication across opencode/claude-code/pi modules)
- Fix lib output: use nixpkgs.lib directly instead of instantiating
a full nixpkgs just to get lib
- Add lib unit tests to flake checks
- Update stale comment in coding-rules.nix
- Add `opencode` flake input pinned to v1.1.27 for stability
- Remove local `pkgs/opencode` derivation and overlay
- Add `opencode` and `opencode-desktop` to `pkgs/default.nix` from input
