donho/mimetools ? reverse-engineered prompt

Build me a Notepad++ plugin that helps with MIME style text conversions.

I want it to let me take selected text in the editor and quickly encode or decode it as Base64, quoted printable, or URL encoded text. It should also be able to decode SAML strings, since that’s useful for debugging login data too. Make it feel like a normal Notepad++ plugin, with menu actions that are easy to find and use on the current selection or clipboard.

Please make it practical and simple, with clear behavior when there’s no selection or the text is invalid. If you need to check anything about how current Notepad++ plugins are usually built, look up the latest docs online. I mainly want a working desktop plugin in C++ that I can build and drop into Notepad++.