chore: update node.js to v26 (#38285)

- bump ci, flake and `@types/node` to node 26
- regenerate flake.lock which is needed for that package
- refactor workflow to use shared composite action

flake.nix

@@ -34,7 +34,7 @@
 
               # only bump toolchain versions here
               go = pkgs.go_1_26;
-              nodejs = pkgs.nodejs_24;
+              nodejs = pkgs.nodejs_26;
               python3 = pkgs.python314;
               pnpm = pkgs.pnpm_10;