feat: Phase 3 & 4 — monitoring, discovery, polish, deployment

Phase 3 — Discovery & Monitoring:
- Network scanner: nmap wrapper + mock fallback, fingerprint service (35 signatures)
- Status checker: ping/http/https/tcp/ssh/prometheus/health per-node checks
- APScheduler: status checks every 60s, WebSocket broadcast
- WebSocket /ws/status: live node status updates to frontend
- Sidebar panels: Pending Devices, Hidden Devices, Scan History
- Auth token persisted to localStorage (survive page refresh)
- 24 new backend tests (scan flow + status_checker)

Phase 4 — Polish & Deployment:
- Auto-layout: Dagre hierarchical TB via Toolbar button
- Export PNG: html-to-image download via Toolbar button
- Scan config modal: CIDR ranges + check interval, GET/POST /api/v1/scan/config
- Dockerfile.backend (Python 3.13 slim + nmap), Dockerfile.frontend (nginx)
- docker-compose.yml with data volume and NET_RAW cap for ping
- scripts/lxc-install.sh: Proxmox VE systemd bootstrap
- README.md: quick-start, config reference, stack overview

frontend/src/stores/authStore.ts

@@ -1,4 +1,5 @@
 import { create } from 'zustand'
+import { persist } from 'zustand/middleware'
 
 interface AuthState {
   token: string | null
@@ -7,9 +8,14 @@ interface AuthState {
   logout: () => void
 }
 
-export const useAuthStore = create<AuthState>((set) => ({
-  token: null,
-  isAuthenticated: false,
-  login: (token) => set({ token, isAuthenticated: true }),
-  logout: () => set({ token: null, isAuthenticated: false }),
-}))
+export const useAuthStore = create<AuthState>()(
+  persist(
+    (set) => ({
+      token: null,
+      isAuthenticated: false,
+      login: (token) => set({ token, isAuthenticated: true }),
+      logout: () => set({ token: null, isAuthenticated: false }),
+    }),
+    { name: 'homelable-auth' }
+  )
+)