CI: install nodejs so JS-based actions run in the arch container

actions/checkout and actions/cache are executed with node inside the
archlinux:latest job container, which has no node by default. Install it
in the first (shell) step, before Checkout, mirroring the Crafter.Build CI.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.forgejo/workflows/deploy.yaml

@@ -23,7 +23,12 @@ jobs:
           pacman-key --init
           pacman-key --populate archlinux
           pacman -Sy --noconfirm --needed archlinux-keyring
+          # nodejs is required for the JS-based actions (checkout, cache) to
+          # run inside this archlinux container — the runner execs them with
+          # node. This shell step needs no node, so installing it here (before
+          # Checkout) is enough.
           pacman -Syu --noconfirm --needed \
+            nodejs \
             clang lld libc++ \
             wasi-libc wasi-libc++ wasi-libc++abi wasi-compiler-rt \
             git curl tar rsync