feat: add SubcommandDeclarationBuilder interface

lib/api.dart

@@ -27,6 +27,7 @@ export 'package:mineral/src/api/common/commands/command_helper.dart';
 export 'package:mineral/src/api/common/commands/command_option.dart';
 export 'package:mineral/src/api/common/commands/command_option_type.dart';
 export 'package:mineral/src/api/common/commands/command_type.dart';
+export 'package:mineral/src/api/common/commands/sub_command_declaration.dart';
 export 'package:mineral/src/api/common/components/action_row.dart';
 export 'package:mineral/src/api/common/components/attached_file.dart';
 // Commons

lib/src/api/common/commands/builder/command_declaration_builder.dart

@@ -5,6 +5,7 @@ import 'package:mineral/src/api/common/commands/command_context_type.dart';
 import 'package:mineral/src/api/common/commands/command_helper.dart';
 import 'package:mineral/src/api/common/commands/command_option.dart';
 import 'package:mineral/src/api/common/commands/command_type.dart';
+import 'package:mineral/src/api/common/commands/sub_command_declaration.dart';
 import 'package:mineral/src/domains/commands/command_builder.dart';
 import 'package:mineral/src/infrastructure/io/exceptions/missing_method_exception.dart';
 import 'package:mineral/src/infrastructure/io/exceptions/missing_property_exception.dart';
@@ -71,6 +72,18 @@ final class CommandDeclarationBuilder implements CommandBuilder {
     return this;
   }
 
+  CommandDeclarationBuilder registerSubCommand(Function subCommandFactory) {
+    final instance = subCommandFactory();
+
+    if (instance is! SubCommandDeclaration) {
+      throw Exception('Factory must return a SubCommandDeclaration instance');
+    }
+
+    final builder = instance.build();
+    subCommands.add(builder);
+    return this;
+  }
+
   CommandDeclarationBuilder createGroup(Function(CommandGroupBuilder) group) {
     final builder = CommandGroupBuilder();
     group(builder);

lib/src/api/common/commands/sub_command_declaration.dart

@@ -0,0 +1,6 @@
+import 'package:mineral/src/api/common/commands/builder/sub_command_builder.dart';
+import 'package:mineral/src/domains/common/utils/listenable.dart';
+
+abstract interface class SubCommandDeclaration implements Listenable {
+  SubCommandBuilder build();
+}