feat: Update session navigation and enhance error handling in data services

apps/mobile/packages/data_connect/lib/src/session/staff_session_store.dart

@@ -1,18 +1,15 @@
 import 'package:krow_domain/krow_domain.dart' as domain;
 
 class StaffSession {
+  const StaffSession({required this.user, this.staff, this.ownerId});
+
   final domain.User user;
   final domain.Staff? staff;
   final String? ownerId;
-
-  const StaffSession({
-    required this.user,
-    this.staff,
-    this.ownerId,
-  });
 }
 
 class StaffSessionStore {
+  StaffSessionStore._();
   StaffSession? _session;
 
   StaffSession? get session => _session;
@@ -26,6 +23,4 @@ class StaffSessionStore {
   }
 
   static final StaffSessionStore instance = StaffSessionStore._();
-
-  StaffSessionStore._();
 }