Add Dockerfile, K8s manifests, and ArgoCD app for OpenShift deployment

Dockerfile

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+FROM node:22-alpine
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci --omit=dev
+COPY server.js ./
+COPY public/ ./public/
+RUN mkdir -p /app/data && chgrp -R 0 /app && chmod -R g=u /app
+ENV DATA_DIR=/app/data
+EXPOSE 3333
+USER 1001
+CMD ["node", "server.js"]