flake.lock: 87 → 8 nodes (1595 → 164 lines)
Only 6 flake inputs remain: flake-parts, nixpkgs, nix-darwin,
home-manager, nixos-unified, agenix. Everything else is pinned
via npins and lazily evaluated through flake-compat, so
`nix develop` and `nix run` no longer fetch/resolve 80+ transitive
dependency nodes.
Modules are unchanged — npins-derived inputs are merged into the
`inputs` attrset passed to mkFlake, preserving the existing
`flake.inputs.foo` / `inputs.foo` interface.
