chore: add MIT License notice to source files and README

cmd/miab/main.go

@@ -1,3 +1,7 @@
+// Copyright (c) 2026 Sławomir Koszewski. All rights reserved.
+// Use of this source code is governed by the MIT License
+// that can be found in the LICENSE file.
+
 package main
 
 import (