Refactor Channel endpoints and data models: replace jingle functionality with bumper templates, update related commands and handlers, and enhance API routes for managing bumper templates. Remove obsolete jingle-related code and adjust channel data structures to support new bumper template features.

backend/src/TeleWave.Application/Broadcast/Bumpers/AddBumperTemplateCommandHandler.cs

@@ -0,0 +1,28 @@
+using LiteCqrs;
+using Microsoft.EntityFrameworkCore;
+using TeleWave.Application.Common.Interfaces;
+using TeleWave.Application.Common.Models;
+
+namespace TeleWave.Application.Broadcast.Bumpers;
+
+public sealed class AddBumperTemplateCommandHandler(IAppDbContext dbContext)
+    : ICommandHandler<AddBumperTemplateCommand, Result<Guid>>
+{
+    public async Task<Result<Guid>> Handle(
+        AddBumperTemplateCommand command,
+        CancellationToken cancellationToken
+    )
+    {
+        var channel = await dbContext.Channels
+            .Include(c => c.BumperTemplates)
+            .FirstOrDefaultAsync(c => c.Id == command.ChannelId, cancellationToken);
+        if (channel is null)
+            return Result.Failure<Guid>(ChannelErrors.NotFound);
+
+        var name = string.IsNullOrWhiteSpace(command.Name)
+            ? $"Заставка {channel.BumperTemplates.Count + 1}"
+            : command.Name.Trim();
+        var template = channel.AddBumperTemplate(name);
+        return Result.Success(template.Id);
+    }
+}