Add Dockerfile and CI

Dockerfile

@@ -0,0 +1,20 @@
+# syntax=docker/dockerfile:1
+FROM node:20-alpine AS build
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci
+COPY . .
+RUN npm run build
+
+FROM nginx:1.27-alpine
+COPY --from=build /app/dist /usr/share/nginx/html
+# Serve SPA on port 3000 with history fallback
+RUN printf 'server { \
+  listen 3000; \
+  server_name _; \
+  root /usr/share/nginx/html; \
+  index index.html; \
+  location / { try_files $uri /index.html; } \
+}\n' > /etc/nginx/conf.d/default.conf
+EXPOSE 3000
+CMD ["nginx","-g","daemon off;"]