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/tests/test_app.py

@@ -0,0 +1,26 @@
+from fastapi.testclient import TestClient
+
+from app.main import app
+
+
+client = TestClient(app)
+
+
+def test_healthz() -> None:
+    response = client.get("/healthz")
+    assert response.status_code == 200
+    assert response.json() == {"status": "ok"}
+
+
+def test_login_and_dashboard() -> None:
+    response = client.post(
+        "/api/v1/auth/login",
+        json={"email": "admin@nexafabric.local", "password": "ChangeMe_UseEnvInstead"},
+    )
+    assert response.status_code == 200
+    token = response.json()["access_token"]
+
+    dashboard = client.get("/api/v1/dashboard", headers={"Authorization": f"Bearer {token}"})
+    assert dashboard.status_code == 200
+    assert dashboard.json()["clusters"] >= 1
+