Implement push notification reminder system with 9 notification types

Adds comprehensive push notification reminders using pg_cron + pg_net:
- Shift check-in reminder (15 min before, with countdown banner)
- Shift check-out reminder (hourly, persistent until checkout)
- Overtime idle reminder (15 min without task)
- Overtime checkout reminder (30 min after task completion)
- IT service request event reminder (1 hour before event)
- IT service request evidence reminder (daily)
- Paused task reminder (daily)
- Backlog reminder (15 min before shift end)
- Pass slip expiry reminder (15 min before 1-hour limit, with countdown banner)

Database: Extended scheduled_notifications table to support polymorphic references
(schedule_id, task_id, it_service_request_id, pass_slip_id) with unique constraint
and epoch column for deduplication. Implemented 8 enqueue functions + master dispatcher.
Uses pg_cron every minute to enqueue and pg_net to trigger process_scheduled_notifications
edge function, eliminating need for external cron job. Credentials stored in vault with
GUC fallback for flexibility.

Flutter: Added ShiftCountdownBanner and PassSlipCountdownBanner widgets that display
persistent countdown timers for active shifts and pass slips. Both auto-dismiss when
user completes the action. FCM handler triggers shift countdown on start_15 messages.
navigate_to field in data payload enables flexible routing to any screen.

Edge function: Updated process_scheduled_notifications to handle all 9 types with
appropriate titles, bodies, and routing. Includes pass_slip_id in idempotency tracking.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

lib/services/notification_bridge.dart

@@ -51,13 +51,25 @@ class _NotificationBridgeState extends ConsumerState<NotificationBridge>
     }
   }
 
-  /// Navigate to the task or ticket detail screen using GoRouter.
-  void _goToDetail({String? taskId, String? ticketId}) {
+  /// Navigate to the appropriate screen using GoRouter.
+  ///
+  /// Supports generic [route] for new notification types, plus legacy
+  /// [taskId], [ticketId], and [itServiceRequestId] fallbacks.
+  void _goToDetail({
+    String? taskId,
+    String? ticketId,
+    String? itServiceRequestId,
+    String? route,
+  }) {
     final router = ref.read(appRouterProvider);
-    if (taskId != null && taskId.isNotEmpty) {
+    if (route != null && route.isNotEmpty) {
+      router.go(route);
+    } else if (taskId != null && taskId.isNotEmpty) {
       router.go('/tasks/$taskId');
     } else if (ticketId != null && ticketId.isNotEmpty) {
       router.go('/tickets/$ticketId');
+    } else if (itServiceRequestId != null && itServiceRequestId.isNotEmpty) {
+      router.go('/it-service-requests/$itServiceRequestId');
     }
   }
 
@@ -96,20 +108,34 @@ class _NotificationBridgeState extends ConsumerState<NotificationBridge>
     });
   }
 
-  /// Extract task/ticket IDs from the FCM data payload and navigate.
+  /// Extract navigation target from FCM data payload and navigate.
   ///
-  /// The FCM data map contains keys such as `task_id` / `taskId` /
-  /// `ticket_id` / `ticketId` — these are the same keys used in the
-  /// background handler ([_firebaseMessagingBackgroundHandler]).
+  /// Prefers the `navigate_to` field (used by scheduled notification
+  /// reminders) and falls back to legacy `task_id` / `ticket_id` keys.
   void _handleMessageTap(RemoteMessage message) {
     final data = message.data;
 
-    final String? taskId = (data['task_id'] ?? data['taskId'] ?? data['task'])
-        ?.toString();
+    // New: use navigate_to route if present (scheduled reminder notifications)
+    final String? navigateTo = data['navigate_to']?.toString();
+    if (navigateTo != null && navigateTo.isNotEmpty) {
+      _goToDetail(route: navigateTo);
+      return;
+    }
+
+    // Legacy fallback for task_id / ticket_id
+    final String? taskId =
+        (data['task_id'] ?? data['taskId'] ?? data['task'])?.toString();
     final String? ticketId =
         (data['ticket_id'] ?? data['ticketId'] ?? data['ticket'])?.toString();
+    final String? isrId =
+        (data['it_service_request_id'] ?? data['itServiceRequestId'])
+            ?.toString();
 
-    _goToDetail(taskId: taskId, ticketId: ticketId);
+    _goToDetail(
+      taskId: taskId,
+      ticketId: ticketId,
+      itServiceRequestId: isrId,
+    );
   }
 
   @override
@@ -138,8 +164,11 @@ class _NotificationBridgeState extends ConsumerState<NotificationBridge>
     ) {
       if (next != null) {
         _goToDetail(
+          route: next.route,
           taskId: next.type == 'task' ? next.id : null,
           ticketId: next.type == 'ticket' ? next.id : null,
+          itServiceRequestId:
+              next.type == 'it_service_request' ? next.id : null,
         );
         // Clear the pending navigation after handling
         ref.read(pendingNotificationNavigationProvider.notifier).state = null;