migrated custom timetable events to Marianum-Connect and refactored push notification handling

lib/push/push_registration.dart

@@ -350,21 +350,26 @@ class PushRegistration {
     }
   }
 
-  /// Registers this device when push is both user-enabled and backend-capable.
-  /// Only registers when the OS notification permission is *already* granted —
-  /// it never triggers the OS prompt itself. Requesting the permission is the
-  /// job of the first Talk visit (see `maybePromptTalkNotifications`), which
-  /// keeps the prompt out of the cold-start path. Safe to call on every start —
-  /// Nextcloud dedups an unchanged registration — which also self-heals a
-  /// device whose registration was lost.
-  static Future<void> syncSubscription({
-    required bool enabled,
-    required bool capable,
-  }) async {
-    if (!(enabled && capable)) return;
+  /// Registers this device whenever the backend advertises the push capability.
+  /// Deliberately independent of the in-app notification toggle: a user who
+  /// turned notifications off stays registered so silent sync pushes keep
+  /// flowing — the display is suppressed downstream via the mirrored flag (see
+  /// [PushRegistrationStore.notificationsEnabled]). Only registers when the OS
+  /// notification permission is *already* granted — it never triggers the OS
+  /// prompt itself. Requesting the permission is the job of the first Talk visit
+  /// (see `maybePromptTalkNotifications`), which keeps the prompt out of the
+  /// cold-start path. Safe to call on every start — Nextcloud dedups an
+  /// unchanged registration — which also self-heals a device whose registration
+  /// was lost.
+  /// Returns whether registration was actually *attempted* (all gates passed).
+  /// Even a partial success persists the `general` device identifier, so the
+  /// caller re-emits telemetry on `true` to reflect the fresh registration in
+  /// the same session instead of lagging until the next launch.
+  static Future<bool> syncSubscription({required bool capable}) async {
+    if (!capable) return false;
     if (!await isOsPermissionGranted()) {
       log('Push: OS notification permission not granted, skipping registration');
-      return;
+      return false;
     }
     final registration = PushRegistration();
     // register() below refreshes an unchanged subscription anyway; the check
@@ -373,6 +378,7 @@ class PushRegistration {
       log('Push: registered endpoints outdated, re-registering');
     }
     await registration.register();
+    return true;
   }
 
   /// Re-registers after an FCM token refresh. The Nextcloud device identifier