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/main.dart

@@ -14,6 +14,7 @@ import 'app.dart';
 import 'theme/app_theme.dart';
 import 'providers/notifications_provider.dart';
 import 'providers/notification_navigation_provider.dart';
+import 'providers/shift_countdown_provider.dart';
 import 'utils/app_time.dart';
 import 'utils/notification_permission.dart';
 import 'utils/location_permission.dart';
@@ -197,7 +198,7 @@ Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
   // Create a unique ID for the notification display
   final int id = DateTime.now().millisecondsSinceEpoch ~/ 1000;
 
-  // Build payload string with ticket/task information for navigation
+  // Build payload string with ticket/task/route information for navigation
   final payloadParts = <String>[];
   final taskId =
       (message.data['task_id'] ??
@@ -209,7 +210,11 @@ Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
       message.data['ticketId'] ??
       message.data['ticket']?.toString() ??
       '';
+  final navigateTo = message.data['navigate_to']?.toString() ?? '';
 
+  if (navigateTo.isNotEmpty) {
+    payloadParts.add('route:$navigateTo');
+  }
   if (taskId != null && taskId.isNotEmpty) {
     payloadParts.add('task:$taskId');
   }
@@ -424,6 +429,25 @@ Future<void> main() async {
     } catch (_) {}
 
     final formatted = _formatNotificationFromData(dataForFormatting);
+
+    // Activate the shift countdown banner for start_15 notifications
+    final msgType = message.data['type']?.toString() ?? '';
+    if (msgType == 'start_15') {
+      // The shift starts 15 minutes from when the notification is sent.
+      // Use scheduled_for from data if available, otherwise estimate.
+      final scheduledFor = message.data['scheduled_for']?.toString();
+      DateTime shiftStart;
+      if (scheduledFor != null && scheduledFor.isNotEmpty) {
+        shiftStart = DateTime.tryParse(scheduledFor) ??
+            DateTime.now().add(const Duration(minutes: 15));
+      } else {
+        shiftStart = DateTime.now().add(const Duration(minutes: 15));
+      }
+      _globalProviderContainer
+          .read(shiftCountdownProvider.notifier)
+          .state = shiftStart;
+    }
+
     String? stableId =
         (message.data['notification_id'] as String?) ?? message.messageId;
     if (stableId == null) {
@@ -483,7 +507,7 @@ Future<void> main() async {
         recent[stableId] = now;
         await prefs.setString('recent_notifs', jsonEncode(recent));
 
-        // Build payload string with ticket/task information for navigation
+        // Build payload string with route/ticket/task information for navigation
         final payloadParts = <String>[];
         final taskId =
             (message.data['task_id'] ??
@@ -495,7 +519,12 @@ Future<void> main() async {
             message.data['ticketId'] ??
             message.data['ticket']?.toString() ??
             '';
+        final navigateTo =
+            message.data['navigate_to']?.toString() ?? '';
 
+        if (navigateTo.isNotEmpty) {
+          payloadParts.add('route:$navigateTo');
+        }
         if (taskId != null && taskId.isNotEmpty) {
           payloadParts.add('task:$taskId');
         }
@@ -554,17 +583,20 @@ Future<void> main() async {
   // initialize the local notifications plugin so we can post alerts later
   await NotificationService.initialize(
     onDidReceiveNotificationResponse: (response) {
-      // handle user tapping a notification; the payload format is "ticket:ID",
-      // "task:ID", "tasknum:NUMBER", or a combination separated by "|"
+      // handle user tapping a notification; the payload format is "route:PATH",
+      // "ticket:ID", "task:ID", or a combination separated by "|"
       final payload = response.payload;
       if (payload != null && payload.isNotEmpty) {
-        // Parse the payload to extract ticket and task information
+        // Parse the payload to extract navigation information
         final parts = payload.split('|');
         String? ticketId;
         String? taskId;
+        String? route;
 
         for (final part in parts) {
-          if (part.startsWith('ticket:')) {
+          if (part.startsWith('route:')) {
+            route = part.substring('route:'.length);
+          } else if (part.startsWith('ticket:')) {
             ticketId = part.substring('ticket:'.length);
           } else if (part.startsWith('task:')) {
             taskId = part.substring('task:'.length);
@@ -572,14 +604,22 @@ Future<void> main() async {
         }
 
         // Update the pending navigation provider.
-        // Prefer task over ticket — assignment notifications include both
-        // IDs but the primary entity is the task.
-        if (taskId != null && taskId.isNotEmpty) {
+        // Prefer route (from scheduled reminders), then task, then ticket.
+        if (route != null && route.isNotEmpty) {
+          _globalProviderContainer
+              .read(pendingNotificationNavigationProvider.notifier)
+              .state = (
+            type: 'route',
+            id: '',
+            route: route,
+          );
+        } else if (taskId != null && taskId.isNotEmpty) {
           _globalProviderContainer
               .read(pendingNotificationNavigationProvider.notifier)
               .state = (
             type: 'task',
             id: taskId,
+            route: null,
           );
         } else if (ticketId != null && ticketId.isNotEmpty) {
           _globalProviderContainer
@@ -587,6 +627,7 @@ Future<void> main() async {
               .state = (
             type: 'ticket',
             id: ticketId,
+            route: null,
           );
         }
       }