Add restore functionality for template management and enhance related components

Implemented a new endpoint for restoring templates to their last applied state, allowing users to revert changes made since the last application. Updated the ScheduleTemplate class to include a snapshot of the last applied state, enabling rollback capabilities. Enhanced the frontend with a restore button in the ChannelDetail component, providing users with a confirmation prompt before executing the restore action. Localization updates were made to support new UI strings in both English and Russian, improving the overall user experience in template management.

backend/src/TeleWave.Application/Programming/Planning/GridScheduleGenerator.cs

@@ -161,7 +161,9 @@ public sealed class GridScheduleGenerator(
 
         await SaveCursorsAsync(result.Cursors, cancellationToken);
 
-        template.MarkApplied();
+        // Снимок вместе с отметкой: применённое состояние — единственная корректная точка отката,
+        // и снимать его надо ровно тогда, когда по нему собрана лента.
+        template.MarkApplied(TemplateSnapshot.Capture(template).ToJson());
 
         await dbContext.SaveChangesAsync(cancellationToken);
         await transaction.CommitAsync(cancellationToken);