Add maintenance management features: implement maintenance endpoints in the API, enhance media upload handling to skip duplicate files, and update frontend routes and translations for maintenance operations.

backend/src/TeleWave.Application/Maintenance/DeleteAllShows/DeleteAllShowsCommand.cs

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+using LiteCqrs;
+using TeleWave.Application.Common.Models;
+
+namespace TeleWave.Application.Maintenance.DeleteAllShows;
+
+/// <summary>Удаляет ВСЕ шоу (с сериями через каскад). Медиа-ассеты остаются в библиотеке.</summary>
+public sealed record DeleteAllShowsCommand : ICommand<Result<int>>;

backend/src/TeleWave.Application/Maintenance/DeleteAllShows/DeleteAllShowsCommandHandler.cs

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+using LiteCqrs;
+using Microsoft.EntityFrameworkCore;
+using TeleWave.Application.Common.Interfaces;
+using TeleWave.Application.Common.Models;
+
+namespace TeleWave.Application.Maintenance.DeleteAllShows;
+
+public sealed class DeleteAllShowsCommandHandler(IAppDbContext dbContext)
+    : ICommandHandler<DeleteAllShowsCommand, Result<int>>
+{
+    public async Task<Result<int>> Handle(
+        DeleteAllShowsCommand command,
+        CancellationToken cancellationToken
+    )
+    {
+        // Серии удаляются каскадом (FK Show → ShowEpisode: OnDelete Cascade).
+        var deleted = await dbContext.Shows.ExecuteDeleteAsync(cancellationToken);
+        return Result.Success(deleted);
+    }
+}