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

LICENSE

@@ -0,0 +1,12 @@
+GNU AFFERO GENERAL PUBLIC LICENSE
+Version 3, 19 November 2007
+
+Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+
+NexaFabric is distributed under the GNU Affero General Public License version 3.
+The full license text is available at:
+
+https://www.gnu.org/licenses/agpl-3.0.txt
+