chore: add Dockerfile and dockerignore

Dockerfile

@@ -0,0 +1,21 @@
+# Credit: https://www.digitalocean.com/community/tutorials/how-to-build-a-node-js-application-with-docker
+
+FROM node:24-trixie-slim AS builder
+
+WORKDIR /app
+COPY ./kittyurl-frontend/package*.json ./
+RUN npm ci && npm cache clean --force
+COPY ./kittyurl-frontend/ .
+RUN npm run build
+
+FROM node:24-trixie-slim AS production
+
+WORKDIR /app
+RUN addgroup --gid 1001 nodejs && \
+    adduser  --gid 1001 --uid 1001 nodejs
+COPY --from=builder --chown=nodejs:nodejs /app /app
+USER nodejs
+
+EXPOSE 6568
+
+CMD ["npm", "run", "preview", "--", "--host", "0.0.0.0", "--port", "6568"]