intent(nix): provide reproducible dev environment for Nix users without requiring NixOS
decision(nix-flake-style): inline forAllSystems via lib.genAttrs + lib.systems.flakeExposed instead of pulling in flake-utils
rejected(flake-utils): adds an extra input for trivial system iteration — modern flakes prefer no dependency for this
decision(nix-shell): mkShellNoCC over mkShell — no C compiler needed for npm-based development
decision(node-version): nodejs_24 to match .tool-versions (24.14.0) used by CI, not Dockerfile's node:22-slim
constraint(nix-formatter): pkgs.nixfmt is the canonical name now — pkgs.nixfmt-rfc-style emits a deprecation warning
learned(nix-fish): official installer skips fish setup; users need to source /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.fish from conf.d
Kazuki Yamada