feat(devops): CI/CD + Docker + Monitoring infrastructure

- Multi-stage Dockerfile (builder+runner, <500MB target)
- docker-compose.yml: app(x4) + postgres + redis + prometheus + grafana + nginx
- .env.example with all required secrets (never hardcoded)
- requirements.txt with all dependencies including prometheus-client, alembic
- GitHub Actions CI: lint (flake8+bandit+safety) + tests + Docker build/push
- GitHub Actions CD: staging deploy -> smoke tests -> production deploy + rollback
- Alembic migration setup + initial PostgreSQL schema (001_initial_schema)
- SQLite→PostgreSQL data migration script
- Prometheus metrics module (HTTP, ML, DB, business metrics)
- Prometheus alert rules (5xx >1%, latency >2s, disk >80%, ML accuracy)
- Grafana dashboard (overview: req/s, p95, ML accuracy, error rate)
- Nginx reverse proxy config (HTTPS/TLS, rate limiting, security headers)
- Structured JSON logging module
- Automated daily DB backup script (pg_dump + 30-day retention)

Branch: feature/devops-cicd

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.gitignore

@@ -78,3 +78,31 @@ patch_*.py
 # Données scraping brutes
 v3_*.json
 v4_*.json
+
+# Environment secrets (NEVER commit)
+.env
+.env.local
+.env.*.local
+!.env.example
+
+# Docker build cache
+.docker/
+
+# Editor
+.vscode/
+.idea/
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Test artifacts
+.pytest_cache/
+htmlcov/
+.coverage
+coverage.xml
+
+# TLS certs (managed by certbot volume)
+infra/nginx/certs/