feat: pre-install docker in node-runner image

- Dockerfile.node extends node:22-bookworm with docker.io
- No need for install step in every workflow
- Values-node.yaml references custom image
- Build and push manually (no CI needed)

k8s/infra/forgejo-runner/Dockerfile.node

@@ -0,0 +1,13 @@
+FROM node:22-bookworm
+
+# Install Docker client (dind sidecar provides the daemon)
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+      docker.io \
+      git \
+      curl \
+      ca-certificates && \
+    rm -rf /var/lib/apt/lists/*
+
+# Verify installations
+RUN docker --version && node --version && git --version