Scaffold plant app - MQTT monitoring for boiler-room equipment

Read-only monitoring/alerting for boilers, water softener, calorifiers
and pumps via a generic MQTT-topic-prefix asset model, so new
equipment can be onboarded without new ingestion code. Threshold and
stale-data alert rules with email + in-app notification.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/Dockerfile

@@ -0,0 +1,13 @@
+FROM node:22-alpine AS build
+WORKDIR /app
+COPY package.json .
+RUN npm install
+COPY . .
+ARG VITE_HOTEL_NAME
+ENV VITE_HOTEL_NAME=$VITE_HOTEL_NAME
+RUN npm run build
+
+FROM nginx:alpine
+COPY --from=build /app/dist /usr/share/nginx/html/plant
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+EXPOSE 80