feat(backend/infra): add Docker configuration for Phase 3

- Create Dockerfile for backend (.NET 9.0 multi-stage build)
- Create Dockerfile for frontend (Node + Nginx multi-stage build)
- Create nginx.conf for frontend with API proxy
- Create docker-compose.yml with db, backend, frontend services
- Add .dockerignore files for backend, frontend, and root
- Configure health checks for all services
- Configure PostgreSQL volume for persistent data

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

.dockerignore

@@ -0,0 +1,40 @@
+# Root .dockerignore for the entire solution
+
+# Git
+.git/
+.gitignore
+
+# Docker files
+Dockerfile
+docker-compose*
+.dockerignore
+
+# IDE
+.idea/
+.vs/
+.vscode/
+*.suo
+*.user
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Build output
+**/bin/
+**/obj/
+**/dist/
+
+# Node modules
+**/node_modules/
+
+# Logs
+*.log
+
+# Test results
+**/TestResults/
+
+# Secrets
+**/appsettings.Development.json
+**/secrets.json
+**/.env*

GermanApp/.dockerignore

@@ -0,0 +1,31 @@
+# .NET Core
+**/bin/
+**/obj/
+
+# User secrets
+**/appsettings.Development.json
+**/secrets.json
+
+# NuGet packages
+**/packages/
+
+# IDE
+.idea/
+.vs/
+*.user
+*.suo
+
+# Git
+.git/
+.gitignore
+
+# Docker
+Dockerfile
+.dockerignore
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Test results
+**/TestResults/

GermanApp/Dockerfile

@@ -0,0 +1,54 @@
+# GermanApp Backend Dockerfile
+# .NET 9.0 Web API Application
+# Multi-stage build for production optimization
+
+# ============================================
+# Build Stage
+# ============================================
+FROM mcr.microsoft.com/dotnet/sdk:9.0.204-alpine3.19 AS build
+WORKDIR /src
+
+# Copy project file and restore dependencies
+COPY ["GermanApp/GermanApp.csproj", "GermanApp/"]
+RUN dotnet restore "GermanApp/GermanApp.csproj"
+
+# Copy everything else and build
+COPY . .
+WORKDIR "/src/GermanApp"
+RUN dotnet build "GermanApp.csproj" -c Release -o /app/build
+
+# Publish the application
+RUN dotnet publish "GermanApp.csproj" -c Release -o /app/publish \
+    --no-restore \
+    -p:PublishReadyToRun=true \
+    -p:PublishSingleFile=false \
+    -p:PublishTrimmed=true
+
+# ============================================
+# Publish Stage
+# ============================================
+FROM build AS publish
+
+# ============================================
+# Runtime Stage
+# ============================================
+FROM mcr.microsoft.com/dotnet/aspnet:9.0.4-alpine3.19 AS runtime
+WORKDIR /app
+
+# Copy published app from publish stage
+COPY --from=publish /app/publish .
+
+# Set environment variables
+ENV DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=false
+ENV ASPNETCORE_URLS=http://+:8080
+ENV ASPNETCORE_ENVIRONMENT=Production
+
+# Expose port
+EXPOSE 8080
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
+    CMD curl -f http://localhost:8080/health || exit 1
+
+# Entry point
+ENTRYPOINT ["dotnet", "GermanApp.dll"]

docker-compose.yml

@@ -0,0 +1,68 @@
+version: '3.8'
+
+services:
+  # PostgreSQL Database
+  db:
+    image: postgres:15-alpine
+    container_name: deutschlernen-db
+    environment:
+      POSTGRES_DB: DeutschLernen
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: postgres
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    ports:
+      - "5432:5432"
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U postgres -d DeutschLernen"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+    restart: unless-stopped
+
+  # Backend API
+  backend:
+    build:
+      context: ./GermanApp
+      dockerfile: Dockerfile
+    container_name: deutschlernen-backend
+    environment:
+      ASPNETCORE_ENVIRONMENT: Development
+      ASPNETCORE_URLS: http://+:8080
+      ConnectionStrings__DefaultConnection: Host=db;Port=5432;Database=DeutschLernen;Username=postgres;Password=postgres
+    depends_on:
+      db:
+        condition: service_healthy
+    ports:
+      - "8080:8080"
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8080/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 10s
+    restart: unless-stopped
+
+  # Frontend
+  frontend:
+    build:
+      context: ./german-app-frontend
+      dockerfile: Dockerfile
+    container_name: deutschlernen-frontend
+    environment:
+      NODE_ENV: production
+    depends_on:
+      backend:
+        condition: service_healthy
+    ports:
+      - "3000:3000"
+    healthcheck:
+      test: ["CMD", "wget", "--no-verbose", "--tries=1", "--spider", "http://localhost:3000/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 10s
+    restart: unless-stopped
+
+volumes:
+  postgres_data:

german-app-frontend/.dockerignore

@@ -0,0 +1,41 @@
+# Node modules
+node_modules/
+
+# npm cache
+npm-cache/
+
+# Dist directory (will be built in container)
+dist/
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Git
+.git/
+.gitignore
+
+# Docker
+Dockerfile
+.dockerignore
+
+# Logs
+*.log
+npm-debug.log*
+
+# Environment files
+.env
+.env.local
+.env.*.local
+
+# Build output
+build/
+
+# Test coverage
+coverage/

german-app-frontend/Dockerfile

@@ -0,0 +1,43 @@
+# GermanApp Frontend Dockerfile
+# React 19 + TypeScript + Vite Application
+# Multi-stage build for production optimization
+
+# ============================================
+# Build Stage
+# ============================================
+FROM node:20-alpine AS build
+WORKDIR /app
+
+# Copy package files
+COPY package*.json ./
+
+# Install dependencies
+RUN npm ci
+
+# Copy source files
+COPY . .
+
+# Build the application
+RUN npm run build
+
+# ============================================
+# Runtime Stage
+# ============================================
+FROM nginx:alpine AS runtime
+WORKDIR /usr/share/nginx/html
+
+# Copy built files from build stage
+COPY --from=build /app/dist .
+
+# Copy nginx configuration
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+
+# Expose port
+EXPOSE 3000
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
+    CMD wget --no-verbose --tries=1 --spider http://localhost:3000/ || exit 1
+
+# Entry point (nginx runs by default)
+CMD ["nginx", "-g", "daemon off;"]

german-app-frontend/nginx.conf

@@ -0,0 +1,41 @@
+server {
+    listen 3000;
+    server_name localhost;
+
+    # Root directory
+    root /usr/share/nginx/html;
+    index index.html;
+
+    # Handle React Router - return index.html for all requests
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    # API proxy to backend (when running in Docker Compose)
+    location /api/ {
+        proxy_pass http://backend:8080;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+    }
+
+    # Health check endpoint
+    location /health {
+        access_log off;
+        return 200 "healthy\n";
+        add_header Content-Type text/plain;
+    }
+
+    # Error pages
+    error_page 500 502 503 504 /50x.html;
+    location = /50x.html {
+        root /usr/share/nginx/html;
+    }
+
+    # Cache static assets
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2)$ {
+        expires 1y;
+        add_header Cache-Control "public, immutable";
+    }
+}