fix: practice defense driving...seal it all

src/StreamShorts.Console/Commands/DefaultCommand.cs

@@ -1,6 +1,6 @@
 namespace StreamShorts.Console.Commands;
 
-internal class DefaultCommand(
+internal sealed class DefaultCommand(
   IFileSystem fileSystem,
   IAnsiConsole console,
   IAudioExtractor audioExtractor,

src/StreamShorts.Console/Hosting/TypeRegistrar.cs

@@ -1,6 +1,6 @@
 namespace StreamShorts.Console.Hosting;
 
-internal class TypeRegistrar(IHostBuilder builder) : ITypeRegistrar
+internal sealed class TypeRegistrar(IHostBuilder builder) : ITypeRegistrar
 {
   private readonly IHostBuilder _builder = builder;
 

src/StreamShorts.Console/Hosting/TypeResolver.cs

@@ -1,6 +1,6 @@
 namespace StreamShorts.Console.Hosting;
 
-internal class TypeResolver(IHost provider) : ITypeResolver, IDisposable
+internal sealed class TypeResolver(IHost provider) : ITypeResolver, IDisposable
 {
   private readonly IHost _host = provider ?? throw new ArgumentNullException(nameof(provider));