chore(nix): use mkShellNoCC for lighter dev shell

Switch from mkShell to mkShellNoCC since this project doesn't require
a C compiler toolchain. This reduces unnecessary dependencies and
speeds up shell initialisation for Node.js/pnpm development.

Author: ryoppippi

flake.nix

@@ -18,7 +18,7 @@
       perSystem =
         { pkgs, ... }:
         {
-          devShells.default = pkgs.mkShell {
+          devShells.default = pkgs.mkShellNoCC {
             buildInputs = with pkgs; [
               # runtime
               nodejs_24