Enhance channel management: add support for preferred weight multipliers and preferred hours in channel shows, update related data models and API endpoints, and implement validation for new properties. Refactor scheduling logic to utilize preferred hours for weight adjustments during show planning.

backend/src/TeleWave.Infrastructure/Persistence/AppDbContext.cs

@@ -25,6 +25,7 @@ public class AppDbContext(DbContextOptions<AppDbContext> options)
     public DbSet<Show> Shows => Set<Show>();
     public DbSet<Channel> Channels => Set<Channel>();
     public DbSet<ScheduleEntry> ScheduleEntries => Set<ScheduleEntry>();
+    public DbSet<BumperTextVariant> BumperTextVariants => Set<BumperTextVariant>();
     public DbSet<BumperAsset> BumperAssets => Set<BumperAsset>();
     public DbSet<AppSetting> AppSettings => Set<AppSetting>();
     public DbSet<Image> Images => Set<Image>();