Update scheduling parameters and refactor channel endpoints: extend HorizonDays to 7 and RetentionDays to 90 in appsettings.json. Consolidate channel-related endpoint logic by removing obsolete files and enhancing the ShowEndpoints with audience and genre management capabilities. Improve error handling and streamline command handlers for channel operations.

backend/src/TeleWave.Application/Programming/Groups/ListGroups/ListGroupsQueryHandler.cs

@@ -0,0 +1,32 @@
+using LiteCqrs;
+using Microsoft.EntityFrameworkCore;
+using TeleWave.Application.Common.Interfaces;
+
+namespace TeleWave.Application.Programming.Groups.ListGroups;
+
+public sealed class ListGroupsQueryHandler(IAppDbContext dbContext)
+    : IQueryHandler<ListGroupsQuery, IReadOnlyList<GroupSummaryDto>>
+{
+    public async Task<IReadOnlyList<GroupSummaryDto>> Handle(
+        ListGroupsQuery query,
+        CancellationToken cancellationToken
+    )
+    {
+        // Список читает кэш статистики, не пересчитывая его: пересчёт идёт при правке состава.
+        return await dbContext
+            .Groups.AsNoTracking()
+            .OrderBy(g => g.Name)
+            .Select(g => new GroupSummaryDto(
+                g.Id,
+                g.Name,
+                g.Description,
+                g.ItemCount,
+                g.UnitCount,
+                g.TotalDuration.TotalSeconds,
+                g.FilterJson != null,
+                g.StatsComputedAt,
+                g.CreatedAt
+            ))
+            .ToListAsync(cancellationToken);
+    }
+}