Initial flame_lua_runtime package

lib/runtime/models/runtime_command.dart

@@ -0,0 +1,43 @@
+import '../protocol/runtime_protocol.dart';
+
+class RuntimeCommand {
+  const RuntimeCommand({
+    required this.type,
+    this.target,
+    this.payload = const {},
+  });
+
+  final String type;
+  final String? target;
+  final Map<String, Object?> payload;
+
+  static RuntimeCommand fromMap(Map<String, Object?> map) {
+    final type = map[RuntimeProtocolField.type];
+    if (type is! String || type.isEmpty) {
+      throw const FormatException('RuntimeCommand.type must be a string');
+    }
+
+    if (!RuntimeCommandType.isSupported(type)) {
+      throw FormatException('RuntimeCommand.type is unsupported: $type');
+    }
+    RuntimeProtocolSchema.ensureKnownKeys(
+      map,
+      allowed: RuntimeProtocolSchema.allowedCommandFields(type),
+      context: 'RuntimeCommand.$type',
+    );
+
+    final targetValue = map[RuntimeProtocolField.target];
+    if (targetValue != null && targetValue is! String) {
+      throw const FormatException('RuntimeCommand.target must be a string');
+    }
+
+    final payload = Map<String, Object?>.from(map)
+      ..remove(RuntimeProtocolField.type)
+      ..remove(RuntimeProtocolField.target);
+    return RuntimeCommand(
+      type: type,
+      target: targetValue as String?,
+      payload: payload,
+    );
+  }
+}