feat: reduce resume cooldown to 30s; add pull-to-refresh to News, Calendar; refresh chat on resume

lib/app.dart

@@ -193,7 +193,7 @@ class _ShellState extends ConsumerState<_Shell> with WidgetsBindingObserver {
   ];
 
   // Minimum gap between app-resume refreshes to avoid hammering the server.
-  static const _resumeCooldown = Duration(minutes: 5);
+  static const _resumeCooldown = Duration(seconds: 30);
   DateTime? _lastResumeRefresh;
   int? _prevTabIndex;
 

lib/screens/calendar/calendar_screen.dart

@@ -67,12 +67,15 @@ class CalendarScreen extends ConsumerWidget {
             ),
             const Divider(height: 1),
             Expanded(
+              child: RefreshIndicator(
+                onRefresh: () async => ref.invalidate(calendarProvider),
                 child: _AgendaList(
                   events:
                       cal.eventsByDay[dateOnly(cal.selectedDay)] ?? [],
                   notifier: notifier,
                 ),
               ),
+            ),
           ],
         ),
       ),
@@ -106,7 +109,12 @@ class _AgendaList extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     if (events.isEmpty) {
-      return const Center(child: Text('No events'));
+      return ListView(
+        children: const [
+          SizedBox(height: 80),
+          Center(child: Text('No events')),
+        ],
+      );
     }
     return ListView.builder(
       padding: const EdgeInsets.symmetric(vertical: 8),

lib/screens/chat/chat_screen.dart

@@ -16,12 +16,27 @@ class ChatScreen extends ConsumerStatefulWidget {
   ConsumerState<ChatScreen> createState() => _ChatScreenState();
 }
 
-class _ChatScreenState extends ConsumerState<ChatScreen> {
+class _ChatScreenState extends ConsumerState<ChatScreen>
+    with WidgetsBindingObserver {
   final _controller = TextEditingController();
   final _scrollController = ScrollController();
 
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addObserver(this);
+  }
+
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState state) {
+    if (state == AppLifecycleState.resumed) {
+      ref.invalidate(messagesProvider(widget.conversationId));
+    }
+  }
+
   @override
   void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
     _controller.dispose();
     _scrollController.dispose();
     // Exit voice mode if the user navigates away mid-session.

lib/screens/news/news_screen.dart

@@ -96,6 +96,8 @@ class _NewsScreenState extends ConsumerState<NewsScreen> {
             ),
             const Divider(height: 1),
             Expanded(
+              child: RefreshIndicator(
+                onRefresh: () async => ref.invalidate(newsProvider),
                 child: ListView.builder(
                 padding:
                     const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
@@ -129,6 +131,7 @@ class _NewsScreenState extends ConsumerState<NewsScreen> {
                 },
               ),
               ),
+            ),
           ],
         ),
       ),