Add production Dockerfiles and nginx config

Backend: installs non-editable, runs uvicorn without reload.
Frontend: multi-stage build, serves static files via nginx with
API proxy to the backend service and SPA fallback routing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/Dockerfile.prod

@@ -0,0 +1,21 @@
+# Production Dockerfile for the frontend
+# Stage 1: Build
+FROM node:24-slim AS build
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm ci
+
+COPY . .
+RUN npm run build
+
+# Stage 2: Serve
+FROM nginx:alpine
+
+COPY --from=build /app/dist /usr/share/nginx/html
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+
+EXPOSE 80
+
+CMD ["nginx", "-g", "daemon off;"]