feat(smart-app): add Docker web build + Traefik integration

smart-app-city/frontend/Dockerfile

@@ -0,0 +1,42 @@
+# Smart App City — Web build (Expo/React Native Web)
+# Build stage
+FROM node:20-alpine AS builder
+
+WORKDIR /app
+
+# Copy package files
+COPY package.json package-lock.json ./
+
+# Install dependencies
+RUN npm ci --legacy-peer-deps
+
+# Copy source
+COPY . .
+
+# Build web version
+RUN npx expo export --platform web --output-dir dist
+
+# Serve stage — lightweight nginx
+FROM nginx:alpine
+
+# Copy built assets
+COPY --from=builder /app/dist /usr/share/nginx/html
+
+# Nginx config for SPA routing
+RUN echo 'server { \
+    listen 80; \
+    server_name _; \
+    root /usr/share/nginx/html; \
+    index index.html; \
+    location / { \
+        try_files $uri $uri/ /index.html; \
+    } \
+    location ~* \.(js|css|png|jpg|jpeg|gif|svg|ico|woff|woff2|ttf|eot)$ { \
+        expires 1y; \
+        add_header Cache-Control "public, immutable"; \
+    } \
+}' > /etc/nginx/conf.d/default.conf
+
+EXPOSE 80
+
+CMD ["nginx", "-g", "daemon off;"]