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/tests/e2e/login.spec.ts

@@ -0,0 +1,7 @@
+import { expect, test } from "@playwright/test";
+
+test("login screen is available", async ({ page }) => {
+  await page.goto("/login");
+  await expect(page.getByText("NexaFabric")).toBeVisible();
+});
+