Bump Node target to 24.18.0 (latest 24.x), matching web-jam-back#869 / JaMmusic#1141. engines.node + .nvmrc 24.16.0 → 24.18.0; CircleCI cimg/node:24.16-browsers → cimg/node:24.18-browsers. Same Node line across app + local dev + CI; latest security/patch fixes.
Bump Node target to 24.18.0 (latest 24.x), matching web-jam-back#869 / JaMmusic#1141. engines.node + .nvmrc 24.16.0 → 24.18.0; CircleCI
cimg/node:24.16-browsers→cimg/node:24.18-browsers. Same Node line across app + local dev + CI; latest security/patch fixes.