feat: Setup projet Classeo avec infrastructure Docker et architecture DDD

Configure l'environnement de développement complet avec Docker Compose,
structure DDD 4 Bounded Contexts, et pipeline CI/CD GitHub Actions.

Corrections compatibilité CI:
- Symfony 8 nécessite monolog-bundle ^4.0 (la v3.x ne supporte que jusqu'à Symfony 7)
- ESLint v9 nécessite flat config (eslint.config.js) - le format .eslintrc.cjs est obsolète

frontend/Dockerfile

@@ -0,0 +1,61 @@
+# syntax=docker/dockerfile:1
+
+# =============================================================================
+# Node.js 22 - Frontend Classeo (SvelteKit)
+# =============================================================================
+
+FROM node:22-alpine AS base
+
+# Install pnpm
+RUN corepack enable && corepack prepare pnpm@10.28.2 --activate
+
+# Set working directory
+WORKDIR /app
+
+# =============================================================================
+# Development stage
+# =============================================================================
+FROM base AS dev
+
+# Create entrypoint script for dev (installs deps if needed)
+RUN echo '#!/bin/sh' > /usr/local/bin/docker-entrypoint.sh && \
+    echo 'set -e' >> /usr/local/bin/docker-entrypoint.sh && \
+    echo 'if [ ! -d /app/node_modules ] || [ ! -f /app/node_modules/.pnpm/lock.yaml ]; then' >> /usr/local/bin/docker-entrypoint.sh && \
+    echo '    echo "Installing pnpm dependencies..."' >> /usr/local/bin/docker-entrypoint.sh && \
+    echo '    pnpm install' >> /usr/local/bin/docker-entrypoint.sh && \
+    echo 'fi' >> /usr/local/bin/docker-entrypoint.sh && \
+    echo 'exec "$@"' >> /usr/local/bin/docker-entrypoint.sh && \
+    chmod +x /usr/local/bin/docker-entrypoint.sh
+
+EXPOSE 5173
+
+ENTRYPOINT ["/usr/local/bin/docker-entrypoint.sh"]
+CMD ["pnpm", "run", "dev", "--host", "0.0.0.0"]
+
+# =============================================================================
+# Build stage
+# =============================================================================
+FROM base AS builder
+
+COPY package.json pnpm-lock.yaml* ./
+RUN if [ -f pnpm-lock.yaml ]; then pnpm install --frozen-lockfile; else pnpm install; fi
+
+COPY . .
+RUN pnpm run build
+
+# =============================================================================
+# Production stage
+# =============================================================================
+FROM base AS prod
+
+ENV NODE_ENV=production
+
+COPY package.json pnpm-lock.yaml* ./
+RUN if [ -f pnpm-lock.yaml ]; then pnpm install --frozen-lockfile --prod; else pnpm install --prod; fi
+
+COPY --from=builder /app/build build/
+COPY --from=builder /app/package.json .
+
+EXPOSE 3000
+
+CMD ["node", "build"]