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/App.test.tsx

@@ -0,0 +1,17 @@
+import { render, screen } from "@testing-library/react";
+import { MemoryRouter } from "react-router-dom";
+import { describe, expect, it } from "vitest";
+
+import { Login } from "../src/pages/Login";
+
+describe("Login", () => {
+  it("renders the product sign-in form", () => {
+    render(
+      <MemoryRouter>
+        <Login />
+      </MemoryRouter>,
+    );
+    expect(screen.getByText("NexaFabric")).toBeInTheDocument();
+    expect(screen.getByRole("button", { name: "Sign In" })).toBeInTheDocument();
+  });
+});