Phase 2 scaffold: mitra online status & pairing logic

Add mitra online/offline status with heartbeat-based auto-offline,
customer-mitra pairing via Valkey pub/sub blast, session management,
and control center dashboard with real-time stats.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

control_center/src/App.jsx

@@ -1,7 +1,9 @@
 import { Routes, Route, Navigate } from 'react-router-dom'
 import { useAuth } from './core/auth/AuthContext'
 import LoginPage from './pages/login/LoginPage'
+import DashboardPage from './pages/dashboard/DashboardPage'
 import MitrasPage from './pages/mitras/MitrasPage'
+import SessionsPage from './pages/sessions/SessionsPage'
 import UsersPage from './pages/users/UsersPage'
 import SettingsPage from './pages/settings/SettingsPage'
 import Layout from './components/Layout'
@@ -17,8 +19,10 @@ export default function App() {
     <Routes>
       <Route path="/login" element={<LoginPage />} />
       <Route path="/" element={<ProtectedRoute><Layout /></ProtectedRoute>}>
-        <Route index element={<Navigate to="/mitras" replace />} />
+        <Route index element={<Navigate to="/dashboard" replace />} />
+        <Route path="dashboard" element={<DashboardPage />} />
         <Route path="mitras" element={<MitrasPage />} />
+        <Route path="sessions" element={<SessionsPage />} />
         <Route path="users" element={<UsersPage />} />
         <Route path="settings" element={<SettingsPage />} />
       </Route>