Phase 3 scaffold: chat engine (WebSocket, FCM, pricing, timer, extension, history)

- Backend: WebSocket plugin, chat/pricing/timer/extension/closure/notification services
- Client app: ChatBloc, pricing dialog, chat screen with message status, extension/goodbye flow, history
- Mitra app: MitraChatBloc, ExtensionBloc, chat screen, extension accept/reject, history
- Control center: free trial, extension timeout, early end config toggles
- DB migration: chat_messages, session_closures, session_extensions, customer_transactions tables

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

mitra_app/lib/features/home/home_screen.dart

@@ -170,13 +170,25 @@ class _StatusToggle extends StatelessWidget {
 class _ActiveSessionsButton extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
-    return Card(
-      child: ListTile(
-        leading: const Icon(Icons.chat_bubble_outline),
-        title: const Text('Sesi Aktif'),
-        trailing: const Icon(Icons.chevron_right),
-        onTap: () => Navigator.of(context).pushNamed('/sessions'),
-      ),
+    return Column(
+      children: [
+        Card(
+          child: ListTile(
+            leading: const Icon(Icons.chat_bubble_outline),
+            title: const Text('Sesi Aktif'),
+            trailing: const Icon(Icons.chevron_right),
+            onTap: () => Navigator.of(context).pushNamed('/sessions'),
+          ),
+        ),
+        Card(
+          child: ListTile(
+            leading: const Icon(Icons.history),
+            title: const Text('Riwayat Chat'),
+            trailing: const Icon(Icons.chevron_right),
+            onTap: () => Navigator.of(context).pushNamed('/chat/history'),
+          ),
+        ),
+      ],
     );
   }
 }