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

backend/app/workers/worker.py

@@ -0,0 +1,12 @@
+import time
+
+
+def main() -> None:
+    print("NexaFabric worker started. Configure Celery queues for production job execution.", flush=True)
+    while True:
+        time.sleep(30)
+
+
+if __name__ == "__main__":
+    main()
+