fix(flutter): request notification permission proactively (TODO-041)

When user enables poke notifications, call requestPermission()
immediately so OS prompt appears on first enable, not lazily.

apps/chanora_flutter/lib/widgets/poke_notification_settings.dart

@@ -1,13 +1,19 @@
 import 'package:flutter/material.dart';
 
 import '../l10n/generated/app_localizations.dart';
+import '../services/poke_notification_service.dart';
 import '../services/poke_preferences_service.dart';
 import 'voice_settings_controls.dart';
 
 class PokeNotificationSettingsDialog extends StatelessWidget {
-  const PokeNotificationSettingsDialog({super.key, required this.preferences});
+  const PokeNotificationSettingsDialog({
+    super.key,
+    required this.preferences,
+    required this.notificationService,
+  });
 
   final PokePreferencesService preferences;
+  final PokeNotificationService notificationService;
 
   @override
   Widget build(BuildContext context) {
@@ -31,7 +37,15 @@ class PokeNotificationSettingsDialog extends StatelessWidget {
                   title: Text(l10n.pokeSettingsEnableLabel),
                   subtitle: Text(l10n.pokeSettingsEnableDescription),
                   value: enabled,
-                  onChanged: (value) => preferences.setPokesEnabled(value),
+                  onChanged: (value) async {
+                    await preferences.setPokesEnabled(value);
+                    // Request notification permission when enabling pokes
+                    // so the OS prompt appears immediately rather than on
+                    // the first poke event.
+                    if (value) {
+                      await notificationService.requestPermission();
+                    }
+                  },
                 ),
               ),
               const Divider(height: 24),