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

frontend/nginx.conf

@@ -0,0 +1,10 @@
+server {
+  listen 80;
+  root /usr/share/nginx/html;
+  index index.html;
+
+  location / {
+    try_files $uri /index.html;
+  }
+}
+