Notifications module

NotificationEndpoints
       │
       ▼
NotificationService
       │
       ├── INotificationRepository → SqlSugarNotificationRepository
       ├── INotificationPreferenceStore → AllowAllNotificationPreferenceStore
       ├── INotificationDeliveryAdapter → NullNotificationDeliveryAdapter
       └── INotificationTemplateStore → (configuration-based)

public class NotificationService
{
    // Create notification → persist to inbox + trigger delivery
    public Task CreateAsync(string userId, NotificationTemplate template,
        CancellationToken ct);

    // Mark individual notification as read
    public Task MarkReadAsync(Guid notificationId, CancellationToken ct);

    // Query user's inbox
    public Task<NotificationInboxPage> GetInboxAsync(string userId,
        int page, int pageSize, CancellationToken ct);
}

public class NotificationTemplate
{
    public string Title { get; }
    public string Body { get; }
    public string Category { get; }  // system, chat, ticket, billing, etc.
    public Dictionary<string, string> Variables { get; }
}

public class NotificationPreference
{
    public string Category { get; }
    public bool InApp { get; }
    public bool Email { get; }
    public bool Sms { get; }
    public bool Push { get; }
}

public class NotificationEntity : TenantSoftDeleteEntityBase
{
    public string UserId { get; set; }
    public string Title { get; set; }
    public string Body { get; set; }
    public string Category { get; set; }
    public bool IsRead { get; set; }
    public DateTimeOffset? ReadAt { get; set; }
}

Ticket created → ticket.created event → NotificationService
Chat mention   → chat.mention event    → NotificationService
Billing alert  → billing.overdue event → NotificationService