build: install Node 24 so JS actions run in the job container

When this image is used as a Gitea Actions `container:`, the runner exec's
`node` inside it to run JS-based actions (actions/checkout, upload-artifact).
The image had no Node, so consuming app builds failed at the checkout step
with `exec: "node": executable file not found in $PATH`.

Pull Node 24 from NodeSource (Noble's apt nodejs is v18) and assert it in
the image sanity check.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Dockerfile

@@ -20,6 +20,15 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
         curl unzip git ca-certificates && \
     rm -rf /var/lib/apt/lists/*
 
+# Node is required for Gitea Actions JS actions (actions/checkout,
+# upload-artifact, ...) to run when this image is used as a job container —
+# the runner exec's `node` inside the container. Noble's apt nodejs is v18;
+# pull the current Node 24 from NodeSource instead.
+ARG NODE_MAJOR=24
+RUN curl -fsSL "https://deb.nodesource.com/setup_${NODE_MAJOR}.x" | bash - && \
+    apt-get install -y --no-install-recommends nodejs && \
+    rm -rf /var/lib/apt/lists/*
+
 # Install the command-line tools into the canonical "latest" location.
 RUN mkdir -p ${ANDROID_SDK_ROOT}/cmdline-tools && \
     curl -fsSL -o /tmp/tools.zip \
@@ -42,7 +51,7 @@ RUN yes | sdkmanager --licenses >/dev/null && \
     rm -rf ${ANDROID_SDK_ROOT}/.android
 
 # Sanity: fail the image build if the toolchain isn't actually usable.
-RUN java -version && sdkmanager --version && \
+RUN java -version && sdkmanager --version && node --version && \
     test -d "${ANDROID_SDK_ROOT}/platforms/${PLATFORM_VERSION}"
 
 WORKDIR /workspace

README.md

@@ -16,6 +16,8 @@ here — and we don't need one.
 - Android cmdline-tools, platform, and build-tools — **baked in**, so prod
   builds don't depend on Google's download endpoint at job time
 - `git`, `curl`, `unzip`
+- Node.js 24 — so Gitea Actions JS actions (`actions/checkout`,
+  `upload-artifact`, …) run when this image is used as a job `container`
 
 Pinned versions live as `ARG`s at the top of the `Dockerfile`: