Add/license

[ChriMarMe]

Resolves issue: #79

[jensdrenhaus]

Nice, there is a tiny GH action for it 👍
Regarding the text in the files: Let's not put the complete license in every file, therefore we have ./LICENSE file but keep it to a three-liner like in other projects. Maybe something like:

// Copyright 2024 Blindspot Software
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

[ChriMarMe]

Updated the license text in .go files according to your wish.