Add broadcast scheduling features: implement Show and Channel entities, enhance AppDbContext and DependencyInjection for broadcasting, and update API routing. Include migration for new database schema and update documentation for broadcast-related functionalities.

backend/src/TeleWave.Domain/Broadcast/AdInsertion.cs

@@ -0,0 +1,11 @@
+namespace TeleWave.Domain.Broadcast;
+
+/// <summary>Политика вставки рекламы на канале.</summary>
+public enum AdInsertion
+{
+    /// <summary>Реклама после целого блока серий.</summary>
+    BetweenBlocks,
+
+    /// <summary>Реклама после каждой серии.</summary>
+    BetweenEpisodes,
+}