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/App.tsx

@@ -0,0 +1,41 @@
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import { BrowserRouter, Route, Routes } from "react-router-dom";
+
+import { Layout } from "./components/Layout";
+import { Dashboard } from "./pages/Dashboard";
+import { FirewallPreview } from "./pages/FirewallPreview";
+import { ListPage } from "./pages/ListPage";
+import { Login } from "./pages/Login";
+import { PolicyDesigner } from "./pages/PolicyDesigner";
+
+const queryClient = new QueryClient();
+
+export function App() {
+  return (
+    <QueryClientProvider client={queryClient}>
+      <BrowserRouter>
+        <Routes>
+          <Route path="/login" element={<Login />} />
+          <Route element={<Layout />}>
+            <Route index element={<Dashboard />} />
+            <Route path="clusters" element={<ListPage title="Clusters" subtitle="Registered Proxmox clusters and sync state." path="/clusters" columns={[{ key: "name", label: "Name" }, { key: "api_url", label: "API URL" }, { key: "mode", label: "Mode" }, { key: "last_sync_status", label: "Sync" }]} />} />
+            <Route path="nodes" element={<ListPage title="Nodes" subtitle="Cluster nodes, capacity, and health." path="/nodes" columns={[{ key: "name", label: "Name" }, { key: "status", label: "Status" }, { key: "cpu_count", label: "CPU" }, { key: "memory_mb", label: "Memory MB" }]} />} />
+            <Route path="workloads" element={<ListPage title="VMs/LXCs" subtitle="Virtual machine and container inventory." path="/vms" columns={[{ key: "name", label: "Name" }, { key: "kind", label: "Kind" }, { key: "status", label: "Status" }, { key: "external_id", label: "VMID" }]} />} />
+            <Route path="networks" element={<ListPage title="Networks" subtitle="Bridges, VLANs, VNets, gateways, tags, and MTU." path="/networks" columns={[{ key: "name", label: "Name" }, { key: "kind", label: "Kind" }, { key: "vlan_id", label: "VLAN" }, { key: "gateway", label: "Gateway" }, { key: "mtu", label: "MTU" }]} />} />
+            <Route path="ipam" element={<ListPage title="IPAM" subtitle="Subnets and tracked IP address states." path="/ipam/addresses" columns={[{ key: "address", label: "Address" }, { key: "status", label: "Status" }, { key: "note", label: "Note" }]} />} />
+            <Route path="tenants" element={<ListPage title="Tenants" subtitle="Tenant and project boundaries for RBAC and policies." path="/tenants" columns={[{ key: "name", label: "Name" }, { key: "description", label: "Description" }]} />} />
+            <Route path="security-groups" element={<ListPage title="Security Groups" subtitle="Logical targets for microsegmentation rules." path="/security-groups" columns={[{ key: "name", label: "Name" }, { key: "description", label: "Description" }]} />} />
+            <Route path="policies" element={<ListPage title="Policies" subtitle="Versioned policy definitions and compile state." path="/policies" columns={[{ key: "name", label: "Name" }, { key: "version", label: "Version" }, { key: "enabled", label: "Enabled" }]} />} />
+            <Route path="designer" element={<PolicyDesigner />} />
+            <Route path="firewall" element={<FirewallPreview />} />
+            <Route path="jobs" element={<ListPage title="Jobs" subtitle="Background task state and execution logs." path="/jobs" columns={[{ key: "kind", label: "Kind" }, { key: "status", label: "Status" }, { key: "progress", label: "Progress" }]} />} />
+            <Route path="audit" element={<ListPage title="Audit Logs" subtitle="Security-relevant activity and change history." path="/audit" columns={[{ key: "created_at", label: "Time" }, { key: "action", label: "Action" }, { key: "object_type", label: "Object" }, { key: "result", label: "Result" }]} />} />
+            <Route path="users" element={<ListPage title="Users" subtitle="Local users, roles, and access state." path="/users" columns={[{ key: "email", label: "Email" }, { key: "display_name", label: "Name" }, { key: "is_active", label: "Active" }]} />} />
+            <Route path="settings" element={<ListPage title="Settings" subtitle="Runtime settings and safety defaults." path="/settings" columns={[{ key: "product", label: "Product" }, { key: "firewall_apply_requires_preview", label: "Preview Required" }, { key: "agent_optional", label: "Agent Optional" }]} />} />
+          </Route>
+        </Routes>
+      </BrowserRouter>
+    </QueryClientProvider>
+  );
+}
+