Refactor bumper template background management: rename background upload endpoint to reflect new functionality, update related command and handler to use image ID instead of extension, and adjust data models to support image references. Remove obsolete background handling code and enhance UI components for improved image selection and display.

backend/src/TeleWave.Domain/Library/ShowEpisode.cs

@@ -18,8 +18,8 @@ public class ShowEpisode
     public string? Title { get; private set; }
     public string? Overview { get; private set; }
 
-    /// <summary>Относительный путь локального кадра или null.</summary>
-    public string? StillPath { get; private set; }
+    /// <summary>Кадр серии — ссылка на запись общего реестра изображений или null.</summary>
+    public Guid? StillImageId { get; private set; }
     public DateOnly? AirDate { get; private set; }
 
     public DateTimeOffset CreatedAt { get; private set; }
@@ -43,13 +43,13 @@ public class ShowEpisode
         Episode = episode;
     }
 
-    /// <summary>Применить метаданные серии (кадр — уже скачанный локально — может быть null).</summary>
-    public void ApplyMetadata(string? title, string? overview, string? stillPath, DateOnly? airDate)
+    /// <summary>Применить метаданные серии (кадр — уже зарегистрирован в реестре — может быть null).</summary>
+    public void ApplyMetadata(string? title, string? overview, Guid? stillImageId, DateOnly? airDate)
     {
         Title = title;
         Overview = overview;
-        if (stillPath is not null)
-            StillPath = stillPath;
+        if (stillImageId is not null)
+            StillImageId = stillImageId;
         AirDate = airDate;
     }
 
@@ -57,7 +57,7 @@ public class ShowEpisode
     {
         Title = null;
         Overview = null;
-        StillPath = null;
+        StillImageId = null;
         AirDate = null;
     }
 }