feat(web): add login page, auth store, API client, and route guard

- API client with axios interceptors: JWT attach + 401 auto-refresh
- Auth store (Zustand): login/logout/loadFromStorage with localStorage
- Login page: gradient background, Ant Design form, error handling
- Home page: dashboard with statistics cards
- App.tsx: PrivateRoute guard, /login route, auth state restoration
- MainLayout: dynamic user display, logout dropdown, menu navigation
- Users API service: CRUD with pagination support

apps/web/src/stores/app.ts

@@ -1,23 +1,15 @@
 import { create } from 'zustand';
 
 interface AppState {
-  isLoggedIn: boolean;
-  tenantName: string;
   theme: 'light' | 'dark';
   sidebarCollapsed: boolean;
   toggleSidebar: () => void;
   setTheme: (theme: 'light' | 'dark') => void;
-  login: () => void;
-  logout: () => void;
 }
 
 export const useAppStore = create<AppState>((set) => ({
-  isLoggedIn: false,
-  tenantName: '',
   theme: 'light',
   sidebarCollapsed: false,
   toggleSidebar: () => set((s) => ({ sidebarCollapsed: !s.sidebarCollapsed })),
   setTheme: (theme) => set({ theme }),
-  login: () => set({ isLoggedIn: true }),
-  logout: () => set({ isLoggedIn: false }),
 }));