Add dockerized app and infra scaffolding

app/frontend/Dockerfile

@@ -0,0 +1,44 @@
+# Frontend image for Next.js (dev server + standalone production runner)
+
+# Dependency + build stage for production
+FROM node:22-bookworm-slim AS builder
+WORKDIR /app
+ENV NODE_ENV=production \
+    NEXT_TELEMETRY_DISABLED=1
+
+# Install dependencies first for better Docker layer caching
+COPY package*.json ./
+RUN npm ci --ignore-scripts
+
+# Copy full source and build standalone output
+COPY . .
+RUN npm run build
+
+# Dev image keeps the toolchain for next dev
+FROM node:22-bookworm-slim AS dev
+WORKDIR /app
+ENV NODE_ENV=development \
+    NEXT_TELEMETRY_DISABLED=1
+COPY package*.json ./
+RUN npm install
+COPY . .
+CMD ["npm", "run", "dev"]
+
+# Production runtime: minimal Node image serving the standalone build
+FROM node:22-slim AS runner
+WORKDIR /app
+ENV NODE_ENV=production \
+    NEXT_TELEMETRY_DISABLED=1 \
+    PORT=3000
+
+# Copy only the files required to serve the built app
+COPY --from=builder /app/.next/standalone ./
+COPY --from=builder /app/public ./public
+COPY --from=builder /app/.next/static ./.next/static
+
+# Drop privileges to the bundled node user for safety
+USER node
+EXPOSE 3000
+
+# Next.js standalone exposes server.js at the root of the standalone output
+CMD ["node", "server.js"]