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/src/api/client.ts

@@ -0,0 +1,79 @@
+const API_BASE_URL = import.meta.env.VITE_API_BASE_URL ?? "/api/v1";
+
+export type Dashboard = {
+  clusters: number;
+  nodes: number;
+  workloads: number;
+  networks: number;
+  open_policy_violations: number;
+  faulty_nodes: Array<{ id: string; name: string; status: string }>;
+  top_talkers: Array<{ name: string; bytes: number }>;
+};
+
+export type Cluster = {
+  id: string;
+  name: string;
+  api_url: string;
+  provider: string;
+  mode: string;
+  last_sync_status: string | null;
+};
+
+export type Network = {
+  id: string;
+  name: string;
+  kind: string;
+  vlan_id: number | null;
+  gateway: string | null;
+  mtu: number;
+  tags: string[];
+};
+
+export type Policy = {
+  id: string;
+  name: string;
+  version: number;
+  enabled: boolean;
+  definition: Record<string, unknown>;
+};
+
+export type AuditLog = {
+  id: string;
+  created_at: string;
+  action: string;
+  object_type: string;
+  result: string;
+};
+
+export function token() {
+  return localStorage.getItem("nexafabric.token");
+}
+
+export function setToken(value: string) {
+  localStorage.setItem("nexafabric.token", value);
+}
+
+export async function api<T>(path: string, init: RequestInit = {}): Promise<T> {
+  const response = await fetch(`${API_BASE_URL}${path}`, {
+    ...init,
+    headers: {
+      "Content-Type": "application/json",
+      ...(token() ? { Authorization: `Bearer ${token()}` } : {}),
+      ...init.headers,
+    },
+  });
+  if (!response.ok) {
+    throw new Error(await response.text());
+  }
+  return response.json() as Promise<T>;
+}
+
+export async function login(email: string, password: string) {
+  const data = await api<{ access_token: string }>("/auth/login", {
+    method: "POST",
+    body: JSON.stringify({ email, password }),
+  });
+  setToken(data.access_token);
+  return data;
+}
+