chore: initial project setup with backend, frontend, CI/CD, and documentation

Add complete NexaFabric project structure including:
- FastAPI backend with SQLAlchemy models, JWT auth, RBAC, audit logging, and provider interfaces
- React + TypeScript frontend with Vite, Tailwind CSS, TanStack Query, and Zustand
- Docker Compose configuration for PostgreSQL, Redis, API, worker, frontend, and nginx
- GitHub Actions and GitLab CI workflows for testing, linting, building, and security scanning
- Environment

.env.example

@@ -0,0 +1,13 @@
+PROJECT_NAME=NexaFabric
+ENVIRONMENT=development
+API_HOST=0.0.0.0
+API_PORT=8000
+DATABASE_URL=postgresql+psycopg://nexafabric:nexafabric@postgres:5432/nexafabric
+REDIS_URL=redis://redis:6379/0
+JWT_SECRET=change-this-to-a-long-random-secret
+JWT_ACCESS_TOKEN_MINUTES=15
+JWT_REFRESH_TOKEN_DAYS=14
+TOKEN_ENCRYPTION_KEY=change-this-fernet-key-before-production
+CORS_ORIGINS=http://localhost:5173,http://localhost:8080
+DEMO_ADMIN_PASSWORD=ChangeMe_UseEnvInstead
+VITE_API_BASE_URL=/api/v1