Add settings endpoints and registration status check: implement new API endpoints for settings management, including registration status retrieval, and update the registration command handler to enforce registration rules based on site settings.

backend/src/TeleWave.Application/Common/Interfaces/IAppDbContext.cs

@@ -3,6 +3,7 @@ using TeleWave.Domain.Auth;
 using TeleWave.Domain.Broadcast;
 using TeleWave.Domain.Library;
 using TeleWave.Domain.Media;
+using TeleWave.Domain.Settings;
 
 namespace TeleWave.Application.Common.Interfaces;
 
@@ -14,6 +15,7 @@ public interface IAppDbContext
     DbSet<Channel> Channels { get; }
     DbSet<ScheduleEntry> ScheduleEntries { get; }
     DbSet<BumperAsset> BumperAssets { get; }
+    DbSet<AppSetting> AppSettings { get; }
 
     Task<int> SaveChangesAsync(CancellationToken cancellationToken);
 }